With regard to their geological occurrence, some are found as constituents, original secondary, of the igneous rocks, formed by chemical agencies; while others occur as vein stones or gangue-materials occuring in association with mineral veins or lodes or filling up pockets or cavities in the rocks.
India is the world’s leading producer of mica and accounts for about 60% of global mica (Abrak) trade. Mica is a group name for several minerals which, though differing in chemical composition and physical properties are characterized by their ability to split readily into very thin plates or flakes which are more or less though elastic and transparent according to variety. The main varieties of mica are:
1. Muscovite (white mica or potash mica)
2. Phlogopite (amber mica)
3. Biotite (black mica)
4. Zinnwaldite (lithium iron mica)
5. Fuschsite (chrome mica)
The principal groups of mica found in India are muscovite, phlogopite and biotite, all being hydro- silicates of these, two account for almost the entire reserves and production. Though Muscovite is a most widely distributed mineral in the crystalline rocks of India, marketable mica is restricted to a few pegmatite veins only, carrying large perfect crystals, free from wrinkling or foreign inclusions.
In block form, it is white, reddish or greenish in colour and is called white mica. Its chief use is as an insulating material in electric goods, another as a substitute for glass in glazing. Mica was known to the ancients who used it in certain Ayurvedic medicines.
Most rocks contain little specks of glistening mica; but those are not in use. To be useful, mica has to be in ‘books’ of atleast 25 mm square size each transparent and free from cracks. The phlogophite also called amber mica, is pale yellowish brown in colour; it is less transparent than muscovite mica. The biotite mica is usually black in thick crystals.
The muscovite and biolite micas occur in small flakes in many igneous rocks including gneisses and schists; they occur is some cases as secondary minerals in metamorphic rocks. Muscovite mica occurs mostly in coarse framed pegmatite dykes of acid igneous origin. Phlogophite, on the other hand, is found only in igneous rocks, particularly pyroxenites which are intruded into metamorphosed limestones and gneisses.
Production and Distribution:
India is the world’s leading producer of sheet mica and accounts for about 60 per cent of global mica trade. Important mica bearing pegmatite occurs in Andhra Pradesh, Jharkhand, Bihar, and Rajasthan.
The total in situ reserves of mica in the country are placed at 59,065 tonnes. The in situ reserves of mica in Andhra Pradesh are 42,626 thousand tonnes, Bihar 12,938 tonnes, Jharkhand 1,494 tonnes and in Rajasthan 2,007 tonnes. Most of the mica product comes from Bihar, Jharkhand, Andhra Pradesh and Rajasthan. India has monopoly in the production of mica, about 60 per cent of world’s total production.
Out of the total production in the country, more than 50% comes from the state of Bihar. The Gaya and Monghyz areas in Bihar and Hazaribagh in Jharkhand are known for the mica production. The mica belt is about 32 kms in width and contains perhaps the richest deposits of high quality ruby-mica in the world.
The main centres of mica production in the belt are in Kodarma reserve forest, Dhorhakola, Domchanch, Dhab Gawan, Tisri, Chakai and Chaka-pathal (Mahesri). Though Bihar is the leading producer of mica, yet mica is often commercially spoken of as ‘Bengal Mica’.
Mica occurs in Palamau, Ranchi and Singhbhum districts. In the pegmatite veins of the Hazaribagh region, lepidolite lethia mica, the source of lithium oxide occurs.
Mica is also produced in Nellore (64 km long and 16 km wide) and Guntur districts of Andhra Pradesh. Guntur in Andhra Pradesh is the centre for splitting and dressing mica. Scrap and waste mica is changed into insulation bricks at Nellore (Andhra Pradesh) Andhra Pradesh are next to Bihar in the total mica production in India. The other districts with workable mica deposits are Vishakapatnam, West Godavari, Krishna (Tiruvur) and Khammam (Kallur). Ruby mica is also found west of Tiruvur and six other localities in Krishna district.
Mica occurs in Banaskantha district in Gobadia hills in Chhota Udaipur, Baroda district and in Devgad Baria. The occurrences are sporadic in nature and do not hold promise for commercial exploitation.
Rajasthan is the third largest producer of mica. There is a long mica producing belt stretching from Udaipur to Ajmer in which Ajmer and Bhilwara are. The chief producing centres.
It’s most important centres are in Bhilwara, Udaipur, Jaipur and Tonk districts. The less important areas are in Alwar, Bharatpur, Jodhpur, Kishangarh, and Sirohi districts. The mineral occurs in coarse granite pegmatitesa, differentiated into quartz cores and feldspathic mica bearing margins.
The few mica deposits known so far possess poor grade greenish mica with cracks and stains. These are found in Bandi Khal and Kunet districts while small books of ruby mica are reported from Mirzapur district.
The other areas with small deposits of mica are Kerala (Alleppey and Kollam), Tamil Nadu (Nilgiri, Coimbatore, Salem and Tiruchirapalli), Madhya Pradesh (Belaghat, Bilaspur, Bastar, Surguja and Chhindwara) and Uttar Pradesh (Mirzapur).
Muscovite deposits occur in a number of localities in Tiruchirapalli, Salem, Coimbatore and the Niigiris districts of Tamil Nadu and Balaghat, Bastar, Narsimhapur, Chhindwara and Sarguja districts of Madhya Pradesh.
Gypsum stands next to coal and iron as a mineral of great importance in the industrial economy of the country. Gypsum is a hydrated sulphate of calcium. As a colourless or white opaque mineral in the form of massive lamps, or transparent plates, gypsum occurs abundantly in nature in sedimentary formations. In some cases, it occurs as transparent crystals (sclenite) associated with clays.
Gypsum being naturally occurring sulphate of calcium finds its most popular use in making of ammonium sulphate. It is also used as a surface dressing for land with considerable benefit to certain crops. It is also an important constituent of cement, improving its durability. Plaster of Paris, partition blocks, sheets and tiles, insulating boards, stuccos and lattices are manufactured from gypsum. Alabaster a massive variety of gypsum is employed for artistic statutory and ornamental purpose.
This mineral is found in sedimentary rocks. It occurs abundantly in massive lumps or transparent plates in sedimentary formations. In some cases, it occurs as transparent crystals associated with clays.
There are five varieties of gypsum which are (a) pure gypsum or selentine which is crystalline in character and is transparent (b) albaster, a dense, massive granular and transluscent variety; (c) satispar, a fibrous variety having a silky lustre; (d) gypsite, an earthy, soft, impure variety containing abudnant small gypsum crystals scattered through clayey or sandy soil; and (e) rock gypsum, a coarse granular, compact massive variety of sedimentary rocks.
Production and Distribution:
The in situ reserves of gypsum are estimated at 383 million tonnes. Out of this two millions are of surgical/plaster grade. 92 million tonnes of fertiliser/pottery grade, 76 million tonnes of cement/paint grade, 13 million tonnes of soil reclamation grade and the rest is unclassified. The production of gypsum is confined to Rajasthan, Tamil Nadu, Jammu and Kashmir, and Gujarat, Rajasthan is the main producer of gypsum followed by Jammu and Kashmir.
The well-known regions of gypsum occurrences are in Jaisalmer, Jodhpur and Bikaner and Jammu and Kashmir which accounts for nearly 86% of the gypsum reserves.
In the tertiary clays and shales of the region, important gypsum occurrences are in Jodhpur, Nagpur and Bikaner. It has nearly 39% of the total reserves. It is also found in Ganga Nagar, Bharatpur, Churu, Jaisalmer, Barmer, Pali and Jodhpur districts.
Jasmar village in Bikaner district has India’s single largest gypsum deposits constituting 17% of the total deposits. The other important deposits in the district occur at Luncaranlar where they are mostly of selentine type and at Dhireva, Jaisalmer, Kaoni, Dhaleran Bharru and Harkassar.
Gypsum deposits are reported in several districts in Tamil Nadu. This veins of gypsum associated with clay and chalky material occur from Tappy and Peria Kurukhai in the south of Chaittali and Asur in the north in Tiruchirapalli district.
Compact gypsum occurs at Nambakkuruchi, Garudamangalam, Sri Kanbur and Kerai in the same districts. It is found as modules in black soil tracts south of Palladam and in the form of conceptions and nodules in the soil in Kokkadi and Kilakurai in Ramanathapuram districts.
Punjab and Himachal Pradesh Border:
Deposits of gypsum occur in the lower spiti valley, especially on the left bank of the spiti opposite to selkar. Small quantities of gypsum occur near subathu on the border of Himachal Pradesh and Punjab.
Beds of gypsum are found in old lacustrine deposits and are of considerable economic interest. The mineral occurs in Sera (North of Lachhaman Jhoola) in Tehri Garhwal, Dehradun, Nainital, Gurucchatti and Kharari Chatti areas in Garhwal districts.
Jammu and Kashmir:
A massive variety of gypsum i.e. Alabster, is found between Ijara and Islamabad north of the Jhelum valley near Bambyar village. It occurs as replacement in dolomite and limestone in Uri tehsil of Baramula district.
Large deposits of good quality gypsum occur in Doda district near Ramban, Batote and Assan. Here rich deposits occur as lenticular bands in the Precambrian salakhal schists or with nummulitic limestone of Eocene Age.
The only notable occurrence is that of crystalline gypsum (selentine) in the marine belts in the border area of Pulicat Lake near Sulpureta in Vellore district, the other areas being Guntur, Adilabad and Prakasham districts.
Important deposits occur in Bhavanagar district near Miani and Keshav in Porbunder area, Kadiali in Junagadh district and in Jamnagar district. Gypsum in veins and thin beds and as crystal distributed in sedimentary state is also found in Saurashtra and Kutch. Hydrated calcium sulphate is obtained as a by-product of salt industry in Gujarat. It is purer than mined gypsum and preferred in several industries.
In addition to mineral gypsum, sea water and phosphoric acid plants form important sources of by-product gypsum. Chemical plants manufacturing hydrofluoric acid and refining borax are the other sources of byproduct gypsum. Marine gypsum is recovered from salt pans during the processing of common salts in coastal regions of Gujarat and Tamil Nadu.
Phospho gypsum is obtained as by-product while manufacturing phosphoric acid by wet process employed by thirteen principal plants located in different parts of the country. Fluro-gypsum is obtained from three plants as a by-product while manufacturing aluminium fluoride and hydro-fluoric acid based on fluorspar. By product boro-gypsum is obtained from a plant which refines calcium borates and produces boric acid and borax.
Limestone is an important mineral and occurs in many formations, some of which are entirely composed of them. Limestone is associated with rocks composed of either calcium carbonate, the double carbonate of calcium and, magnesium or mixture of these two constituents. It also contains small quantities of silica, alumina, iron oxides phosphorus and sulphur.
Limestone deposits are of sedimentary origin and exist in almost all the geological sequences from Pre-Cambrian to recent except in Gondwana. In the Cuddapah, Bijawar, Khondalite and Aravalli groups, limestones attain considerable development, some of them being of great beauty and strength. Vindhya limestones are extensively quarried in Rajasthan and form a source of building stone as valued as that of lime and cement.
Production and Distribution:
The total in situ reserves of limestone of all categories and grades are placed at 1, 69,941 million tonnes. The total conditional reserves have been estimated at 3,713 million tonnes. The major share of its production comes from Madya Pradesh, Chhattisgarh, Andhra Pradesh, Gujarat, Rajasthan, Karnataka, Tamil Nadu, Maharashtra, Himachal Pradesh, Orissa, Bihar, Uttarakhand and Uttar Pradesh.
The remaining part comes from Assam, Haryana, Jammu and Kashmir, Kerala and Meghalaya.The Production of limestone was at 238 million tonnes in the year 2010-11 As much as 87% of the total output in the year 2010-11 was contributed by seven principal States; Andhra Pradesh 22% Rajisthan 18% Madhy Pradesh (13%) Gujarat (9%) Tamil Nadu Chhattisgarh and Karnataka (8%) each.
Although almost all the states of India produce some quantity of limestone, about three-fourths of the total limestone of India is produced by five states of Madhya Pradesh, Andhra Pradesh, Rajasthan, Gujarat and Karnataka.
Cuddapah, Guntur, Krishna, Khammam, Kurnool, West and East Godawari and Nalgonda districts of Andhra Pradesh possess about 20% of the total reserves of cement grade limestone in the country. The great thickness of limestone together with shales and quartzites, constituting the Palnad series of Hyderabad and adjoining areas shows calvarisations in the rock-types. But in the main conforms to the argillaceous and calcareous nature of the system.
Vindhyan limestones are extensively queried in Rajasthan. Ajmer, Jaipur, Pali, Sawai Madhopur, Jhunjhunu, Banswara, Jodhpur, Sirohi and Bundi district of Rajasthan contain about 13% of the total reserves. Flaggy limestone in the state, known popularly as ‘Kota’ stone occurs in varying colours from light brown to blue and grey with fine-grained texture near Suket, Kumet, Salelkheri, Hirakheri, Morak and Kurka.
Gulbarga, Bijapur and Shimoga districts of Karnataka have 22% of the reserves. Limestones from Shahabad, Wadi and places in Gulbarga districts of Karnataka state are widely used. The other main producing districts are Chitradurg, Tumkur, Belgaum, Bijapur, Mysore and Shimoga.
Madhya Pradesh possesses 36% of the country’s total reserves of fluxgrade limestone, most of these in Bilaspur, Jabalpur, Rewa, Satna and Raipur districts. It is the largest producer of limestone.
Junagarh, Amreli, Kutch, Banas Kantha and Surat districts of Gujarat have about 11% of the reserves. The rock known as Junagarh limestone is mainly composed of fragments of calcareious shells cemented by lime. The other important producing districts are Kheda and Junagarh.
There are sizeable deposits in Meghalaya, Khasi and Jaintia Hills districts; in Assam, Nowgong and Sibsagar districts; in Maharashtra, Yeotmal, Chandrapurand Nanded districts; in Uttranachal, Dehradun, Pithoragarh and Mirzapur in Uttar Pradesh; in Tamil Nadu, Salem, Tirunelveli, Tiruchirapalli, Ramanathapuram, Coimbatore and Madhurai districts.
The other important districts are the Bilaspur, Kangara and Chamba in Himachal Pradesh, Mahendragarh and Ambala in Haryana, Nagawn and Sibsagar in Assam, Darjeeling and Jalpaiguri in West Bengal and Anantnag and Jammu in Jammu and Kashmir. The nummulitic limestones of the extra-peninsular districts, viz., Hazara, Punjab and Assam are an enormous repository of pure limestone.
Limestone with more than 10 per cent MgCo3 is called dolomitic; when the percentage rises to 45, they are true dolomites. Both these are fairly distributed in the Himalayas and other parts of India. Dolomite, a double carbonate of calcium and magnesium finds application principally in the iron and steel industry. Economic uses of dolomite are chiefly metallurgical, as refractories; as blast furnace flux; as a source of Co2 gas and magnesium salts and other minor uses.
Production and Distribution:
Dolomite occurrences are widespread in almost all parts of the country. The total in situ reserves of all grades of dolomite are 7,349 million tonnes. The major share of about 90 per cent reserves is distributed in the states of Madhya Pradesh, Chhattisgarh, Orissa, Gujarat, Karnataka, West Bengal, Uttar Pradesh and Maharashtra. The reserves of BF and SMS grades are large, but those of refractory grade at 425 million tonnes constitute only 5.8 per cent of the all India reserve.
The production of dolomite at 5065 thousand tonnes 2010-11. Andhra Pradesh (21%) Chhattisgarh (27%) and (Odisha 22%) were the principal producing states of dolomite. The country’s total reserves of dolomite are estimated at 4,967.5 million tonnes, of which 56% are located in Odisha and Madhya Pradesh. The other main dolomite producing states are Gujarat and Bihar.
Birmitrapur area in the Sundargarh district (Orissa) has over 20% of the country’s total reserves. Other deposits in this district are in Hathibari, Khatepur, Beldih and Lifripara. Orissa is the largest producer of dolomite. In Gangapur area, they occur near Sukra and extend for a total length of about 100 kms. The Kendujhar district also possesses dolomite.
A total of 877 million tones of dolomite have been estimated from various parts of the state. Dolomite Occurs in Bastar, Bilaspur and Janjgir.
Dolomite occurs in the district of Balaghat, Bastar, Bilaspur, Chhindwara, Durg, Hoshangabad, Jabalpur and Jhabua. Madhya Pradesh accounts for 34% of the total reserves. Important deposits occur at Chhatane, Hirri, Pendidih, Dhurarabatta, Atta and Baradwar in Bilaspur district and Kodwa-Mohabatta in Durg district.
Dolomite occurs in the Banda, Dehradun, Nainital and Tehri Garhwal districts.
Deposits of dolomite are found in the districts of Belgaum, Bijapur, Chitradurga, Mysore, Uttar Kannada and Tumkur.
The districts of Chandrapur, Nagpur and Yeotmal have been reported to have recoverable deposits of all grades of dolomite. The Rajpur locality in Yeotmal district possesses over 4% of the country’s total reserves.
Gujarat is the third largest producer of dolomite in India accounting for over 14 per cent of the total production of the country. The districts of Bhavnagar and Vadodara in Gujarat are known to have recoverable reserves of dolomite estimated to be 696.33 million tonnes.
Dolomite occurs in bands to the north of Chaibasa in Singhbhum district and near Banjari in Rohtas district. Some dolomite occurs in Palamau district.
Dolomites of Salem and Tirunelveli are used for the manufacture of bleaching powder and other chemicals off the coast near Tuticorin, there are high grade coralline limestone-deposits used by chemical industry.
Dolomite is consumed in iron and steel, ferro-alloys, fertiliser, glass, alloy steel and several other industries. Dolomite produced at Baradam, Hardi and Hirri in Bilaspur district (Madhya Pradesh) is supplied to the steel plant at Bhilai. The production from Birmitrapur is consumed by the steel plants at Rourkela, Jamshedpur and Burnpur. Most of the production in Gujarat is pulverised into chips.
Among the other producers are Banda, Dehradun, Mirzapur, Nainital and Tehri Garhwal in Uttarakhand; Anandpur, Kurnool and Khammam in Andhra Pradesh; Kamang in Arunachal Pradesh; Shimla, Solan, Mandi in Himachal Pradesh; Ajmer, Alwar, Bhilwara, Jaipur, Jaisalmer, Jhunjhunu, Jodhpur, Nagaur, Pali, Sawai Madhopur, Sikar and Udaipur in Rajasthan.
Also known as talc and sandstone, steatite is a hydrous silicate of magnesium. It occurs in ultra basic rocks and metamorphosed dolomitic limestone chiefly in Archaean and Dharwar rocks of the Peninsula. In its geological relations, steatite is often associated with dolomite and other magnesian rocks. Being massive compact, structure less and easily scratchable, steatite is put to a number of uses.
Because of its smooth uniform structure and soapy feel, it is popuarly known as soapstone, sometimes called ‘potstone’. Paper industry, soap and detergents, insecticides, ceramics, cosmetics, fertilizers, paints, rubber, textile and vanaspati are some of the important industries in which steatite is used.
Production and Distribution:
Steatite mainly occurs in Rajasthan, Uttar Pradesh, Kerala, Maharashtra and Madhya Pradesh. The production of steatite in the year 2010-11 was at 896 thousand tonnes. Rajasthan the principal state accounted for 74% of the total production in 2010-11.
In Anantapur distirct, a very fine variety occurs; the estimated reserves are a little over 1. 4 million tonnes. There are also several other occurrences of steatite in the Kurnool, Nellore, Chittoor, Cuddapah, Khammam and Karimnagar districts. The steatite from Kurnool district is said to be of ‘Lava-grade’. The metamorphosed magnesium limestone of the Cuddapah system contains most of the steatite reserves.
Steatite occurs in the districts of Giridih and Singhbhum.
Occurrences of steatite have been reported from the districts of Chikmaglur, Hassan, Mandhy, Mysore, Raichur and Tumkur districts; the total recoverable reserves in the state being 7.415 million tonnes.
Madhya Pradesh and Chhattisgarh:
Steatite occurs in large quantitites in the ‘Marble Rocks’ near Jabalpur. There are also deposits near Rupaund on the Katni-Bilaspur branch of the South Eastern Railway. A workable deposit of talc occurs near Kumbi in Alirajpur, Jhabua district. Occurrences are also reported from the districts of Dhar, Durg and Narsimhpur.
Steatite deposits are located in the districts of Cannanore and Wynad where 8.131 million tonnes of recoverable reserves of steatite have been estimated.
The districts of Bhandara, Ratnagiri and Sindhudurg posses recoverable reserves of steatite estimated at 7.233 million tonnes.
Deposits occur in Balasore (Nilgiri), Sundargarh (Bonai), Cuttack (Sukinda), Keonjhar and Sambalpur districts.
The state possesses the largest reserves of steatite in the country. There are around 152 large and small deposits scattered throughout the state. The large deposits of superior quality steatite occur in Gisgarh, Morra-Bhanderi and Dogeta in Jaipur district, and Jeoria (Ghevaria), Lakhavali and Deopura in Udaipur district. Occurrences are recorded from Alwar, Banswara, Ajmer, Bharatpur, Dungarpur, Bhilwara, Chittorgarh, Jhunjhunu, Siroly, Sawai Madhopur and Tonk district.
Soapstone occurrences are known near Tiruchirapalli and from Omalur taluk of Salem district. Besides above, steatite deposits are reported from the districts of Coimbatore and North Arcot.
It occurs in association with magnesite deposits in Bhageshwar, Deolthal, Deoldhar, in Almora district. A mineral similar to soapstone in some of its properties, pyrophyllite, is found at Garahri in Hamirapur district and near Bijri and Dhaukua in Jhansi district. Steatite has also been reported from the districts of Chamoli and Pithoragarh.
Small occurrences of talc are located on the hill slopes of the Darjeeling Himalayas near the Sikkim border, at a distance of about 1.5 km north of Gokaer and about 16 km north-west of Darjeeling town. The material varies in quality and grades from impure greenish variety to white massive talc. Some of these pockets have been quarried since 1952.
Numerous occurrences of talcose-chlorite-schists and talc schists have been noticed in Bankura and Jalpaiguri districts. These rocks are suitable for use as potstone and are locally used for carving out pots and utensils of various designs.
India has one of the world’s richest deposits of Kyanite. Kyanite occurs in metamorphic aluminous rocks and its primarily used in metallurgical, ceramic, refractory, electrical glass, cement and a number of other industries due to its ability to stand high temperature.
It is also used in making sparking plugs in automobiles. Kyanite is a silicate of aluminium, Al2, 03, Si0, and have the same chemical composition as andalusite, sillimanite and kyanite. Owning to their possessing certain valuable properties of refractories to stand high temperatures in metallurgical industries especially in the manufacture of glass and ceramics.
Production and Distribution:
The total in situ reserves of Kyanite are 8.1 million tonnes. Besides conditional resources of 95.3 million tonnes of Kyanite are also estimated. Kyanite deposits are located in Maharashtra, Karnataka, Jharkhand, Rajasthan and Andhra Pradesh.
Reserves of Kyanite have been reported from Khammam and Nellore districts. Cyrstals of Kyanite have been found in the garnet mines of Garibpeta, west of Kerissa, Kunda and northwest of Saidpuram and Chundi area in Khammam districts of Andhra Pradesh.
Kyanite occurs mainly in Singhbhum as kyanite quartz rock and as massive kyanite- rock in beds of considerable size in the Archean schists; Kyanite occurs along the northern flank of the copper belt for a distance of about 130 km in Singhbhum district The deposits of Kyanite at Lapsa Buru near Raj Kharswan has been the largest in the world and also the best in quality but now it is nearly exhausted.
Kyanite is abundant in the schists and granites exposed near Kanaur and Bhabeh and in many parts of Bashaher where its beautiful colour has often led to its being mistaken for sapphire; but Kyanite which occurs in blades is less hard than other refractories and breaks easily into small rectangular blades.
The districts of Bhandara and Nagpur possess kyanite, of all grades. It occupies the second position among the major states of India.
Kyanite occurrences have been found in a number of localities in Karnataka. A bladed variety occurs in Thirumalpur locality of Hassan district, massive faint blue Kyanite is found in Mavinkere area of the same district. Small occurrences are reported from east of Hole Narsipur in Hassan district; Malleswara Betta, Kallahalli, Mundanhalli and Itna in Mysore district; Sringeri area in Chikmagalur district and Halalkare taluka of Chitradurga district.
In Orissa, minor deposits occur near Torodanali in Dhenkanal district; at Panijia between Kuldih and Gundipani and Karpal in Mayurbhanj district; and south of Sialjor, near Kodumunda in Sundargarh district.
Kyanite occurs near Kishangarh and Sansera in Udaipur district; Pansal in Bhilwara district and near Dewal and Warlia in Dungarpur district.
Bluish blades of Kyanite occur in certain rocks of Darjeeling and Bankura districts. The principal producers of Kyanite in India are the Bihar State Mineral Development Corporation Ltd. (BSMDCL) and the Hindustan Copper Ltd. (HCL). Recently Karnataka has emerged as the largest producer with 46% of the production.
Sillimanite occurs in the metamorphic aluminous rocks and India has rich reserves of Sillimanite. The occurrence and uses of silimanite are same as Kyanite. About 83% of India’s sillimanite reserves are located in the states of Tamil Nadu and Orissa.
The mineral occurs at 1,000 m- height in 21 scattered deposits in the vicinity of Sonapahar, Nongpur and Nongbain villages in the Nongation area of Meghalaya and are worked by the Bharat Refractors Ltd. Most of the deposits contain sillimanite admixed with corrundum, several deposits contain only sillimanite and a few only corrundum. The mineral occurs in the form of massive boulders in highly aluminous rocks.
Production and Distribution:
The total in situ reserves of sillimanite in the country are 58.8 million tonnes. The conditional resources are estimated to be 5.9 million tonnes. Sillimaniite resources are in Tamil Nadu, Orissa, Kerala, Andhra Pradesh, and West Bengal with minor occurrences in Assam, Jharkhand, Karnataka, Madhya Pradesh, Maharashtra, Meghalaya and Rajasthan.
Sillimanite deposits have been recorded from the districts of Kanyakumari, Tirunevelli, Tiruchirapalli, Coimbatore and some other places in the state.
More than four-fifths of India’s sillimanite reserves occur in the Khasi plateau off in Meghalaya. The Meghalaya minerals possess 94.85% sillimanite, 3.24% corrundum, 0.80% hematite and 0.45% ilmenite.
The deposits of sillimanite in Sonapahar occur as outcrops of natural rocks and boulders sometimes of big size. The Khasi hills sillimanite has an average content of 61 per cent of alumina, 36% of silica and thus, very nearly reproduces the proportions considered ideal in the case of mullite and therefore is valuable for refractory material.
The mineral occurs at 1,000 m height in 21 scattered deposits in the vicinity of Sonapahar, Nongpur and Nongbain villages by the Bharat Refractories Ltd.
Bhandara (Pohara Bodki Mine) districts of Maharashtra contribute 27% of the total output.
The beach sands of Kerala contain 5 to 6% sillimanite. Presently it is being recovered as by product accounting for 65% of the total output.
Deposits of all grades of sillimanite are found in Pipra in Sidhi district. The deposit is about 800 m long and 64 m wide. Less important deposits occur east of Samasthi, north of Chittaguppa and near Kareapal in Bastar district.
Small occurrences have been reported from Gaya and Hazaribagh districts of Bihar, Karbi, and Anglong in Assam. The IRE’s Orissa Sand complex in the coastal region of Chatrapur in Ganjam district, Orissa has a capacity of 30,000 type of granular sillimanite.
Graphite is a mineral which is exclusively formed of finely crystalline form of carbon. It is used for ‘lead’ in pencils in the making of crucibles for metal smelting, as carbon brushes in electric motors, and as a ‘moderator’ in atomic reactors. The greater part of the output is poor in quality and is generally used as paint pigment or for coating the insides of moulds for smooth finish.
Production and Distribution:
The in situ reserves of graphite are 16 million tonnes. Orissa is the major producer of graphite. Almost the entire reserves of Tamil Nadu under proved category are in Ramanathapuram district. Deposits of commercial importance are located in Andhra Pradesh, Jharkhand, Gujarat, Karnataka, Kerala, Madhya Pradesh, Maharashtra, Orissa, Rajasthan and Tamil Nadu.
Graphite reserves are located in Tirunelveli and Madurai districts and near Poonvandi, Arsanur and Kirnur in Ramanathapuram. Some deposits are also found in Arumanallur, Todagamalai and Kandasawamipuram in Kanya Kumari districts.
Graphite deposits of 55-60% carbon occur at Babupali, Dengsurgi, Biliangora, Bughmunda, Komna and other parts of Kalahandi districts; Titilagarh, Darpagarh, Munbahal, Belgaon, Patnagarh and other areas of Bolangir district; near Sargipalli, Padampur and Rampur in Sambalpur district; Majikalam Arugali, Karrigudda and other parts of Koraput and in Phulpani district.
Graphite deposits around Peddanakonda have a fixed carbon content of 40 to 65 per cent. Important areas include east Godavari and west Godavari districts (areas like Rampa Chodavaram, Reddi Bodiar and Haripuram) Krishna district, Khamamet district, Visakhapatnam, Guntur and Bunderu.
Apatites and Rock Phosphates:
Native phosphates, as Apatites [Ca/5 F(Po4)5] or rock phosphates, as concentrations are highly valued now as artificial fertilizers or manures, either in the raw condition or after treatment with sulphuric acid to convert them into acid or super phosphates. The mineral apatite and phosphate rock modules are grouped in this category. Phosphorus is an essential ingredient in building up the fertility of soil.
The principal uses of these minerals are for the manufacture of phosphatic fertilizers containing phosphates in a soluble form or for the manufactures of elemental phosphorus and phosphoric acid.
Small quantities are used in the manufacturer of high phosphorous pig iron for spun pipes and other casting purposes, manufactures of matches, chemicals and plastics. Apatite is the by-product of phosphate from the slag of the basic Bessemer and basic hearth steel furnaces. India is poor in phosphatic minerals.
Production and Distribution:
Apatite deposits of commercial importance known so far are confined to Puruliya district of West Bengal, Singhbhum district of Bihar and Visakhapatnam district of Andhra Pradesh. The production of Phosphorite rock phosphate at 215 thousand tonnes increased by 34.05% in the year 2010-11. Rajasthan alone accounted for 94% of the total production in India. Madhya Pradesh contributed the reaming 6% of the production.
Apatite deposits have also been reported from Ajmer, Dungrapur and Jaisalmer districts, the P2O5 content of these deposits is 15-30 per cent. About 37 lakh tonnes of phosphorite has been provided in the Jhamar Kotra area near Udaipur.
The state produces more than three-fourths of the total production of apetite. Almost the entire output comes from the Beldih open-cast mines of the West Bengal mineral development and Trading Corporation in Puruliya district. The ore produced has a content of 20% P2O5.
The district of Visakhapatnam has Apatite reserves especially near Sitarampuram area of Visakhapatnam district. The phosphate content is less than 35 per cent. It is found in the zone of magnetite vermiculite running in parallel veins in diopside gneiss and granulites.
Massive apatite occurs as an abundant constituent of the mica-pegmatites of Hazaribagh and of the mica-periodatite dykes. Fairly large deposits of apatite also occur over a belt of 64 kms in the northern part of Singhbhum district.
Phosphatic deposit is also found in lenticular aggregates in the Dharwar rocks of Dalbhum in Singhbhum. Rock phosphates occur in veins and lenses in patches running for 60 kms from Itagarh, west of Jamshedpur to Khejurdhari south of Mosabani, in Singhbhum district. The P2O5 content of these deposits is 11-20 per cent.
Phosphatic deposits occur in connection with the Cretaceous beds of Tiruchirapalli, where phosphate of lime occurs in the form of septarian nodules disseminated in the clay beds. Apatite also occurs in some schistose rocks in Dharmapuri and North Arcot districts.
The Khatamba open cast mine in Jhabua district and Hirapur in Chhatarpur and Sagar districts produce about 4-5% of India’s total output of phosphorite.
Fairly extensive deposits overlying the Krol limestone near Mussoorie, rich in tricalcium phosphates, have been lately discovered. They occur in the form of nodules and layers.
The nodules contain 76 per cent calcium phosphate while the phosphatic rocks contain about 65 per cent. This rock occurs in Dehradun, Tehri Garhwal and Lalitpur areas. The grades of P2O5 vary widely. Superphosphate manure in India is manufactured from imported rock-phosphate and bone-meal.
Magnesite is one of the important minerals used in the manufacture of basic refractories, which in turn, find an application in the iron and steel industry. Magnesium does not occur in nature in the Free State. It commonly occurs in combination as a carbonate, known as magnesite, which is a hard, white massive mineral occurring as earthy lumps, generally as a network of veins in highly weathered ultrabasic rocks.
Magnesite is believed to be an alteration product of dunites (periodite) and other basic magnesian rocks. Magnesite occur in nature usually as a secondary deposit formed due to alteration of ultra basic rocks mostly serpentines and also as replacement deposits in carbonate rocks and as bedded deposits and vein fillings.
The most familiar use of magnesium for the common man is the magnesium wire giving a brilliant glow of incandescent light. Large deposits of magnesite (MgCO3) occur in the district of Salem as veins associated with other magnesian rocks such as dolomite, serpentine etc.
It is also used in for manufacturing Sorel cement (magn esium oxychloride) and magnesium salts. Raw magnesite is dead burnt for making refractory bricks and caustic and calcined for non-refractory uses.
Production and Distribution:
The total in situ reserves of magnesite are about 415 million tonnes of which 76 million tonnes are in the proved category. Major deposits of magnesite are found in Uttarakhand, Tamil Nadu and Rajasthan while minor occurrences are in Jammu and Kashmir, Karnataka, Himachal Pradesh and Kerala.
One of the largest deposits of magnesite in the world and the largest in India known so far occurs near Salem town at the Chalk Hills known locally in Tamil as ‘Sunnambu Karadu’. This magnesite is of a high degree of chemical purity (MgO 46.4 per cent) is easily obtained and when calcined at a high temperature, yields a material of great refractoriness.
The deposits, occurring in irregular veins in intrusive ultrabasic rocks, spread over an area of 18.13 kms. The veins are of dyke, lens and reticulate types. The other areas where magnesite occurs are the districts of Dharampuri, Nilgiri, North Arcot, Periyar and Tirunelveli Small deposits of similar magnesite occur in Chettipati, Siranganur, Sirapalls, in Salem district and near Pavitram in Tiruchirapalli district.
Magnesite veins are found in serpentine rocks derived from ultrabasic rocks in Dod Kanya and Dod Katur in the districts of Hassan and Mysore which are transversed by the same veins as from Tamil Nadu stretching upto Coorg on the West Coast. Other reserves are found in Sinduvalli, Solepur, Navinahalli Burnpur and Kuppa and in Kollegal taluka.
In Hassan district, inferior deposits occur near Holenarsipur, Sunnahat, Hasur, Dodkadnur, Kabbur, Idegondane halli and Hasadpur. Veins of magnesite form a patch of dunite on the eastern slopes of Ennahole, Rangappanbetta and other places in Holenarsipur.
Himachal Pradesh and Jammu and Kashmir:
Recoverable reserves of all grades of magnesite have been estimated from the Chamba district of Himachal Pradesh and from Udhampur district of Jammu and Kashmir. Mahasu and Sirmur in Himachal Pradesh also have reserves of Magnesite.
Reserves are found in Balasore. Cuttack, Mayurbhanj and Sundargarh in Orissa.
Magnesite occur in the districts of Ajmer, Pali; Udaipur, Dungarpur and Nagaur districts of Rajasthan.
Over a quarter reserves of magnesite occur in Almora district of Uttarakhand. Here good quality magnesite occurs in narrow bands of variable thickness in massive dolomite between Someshwar and Bageshwar near Agar, Chahana, Dewaldhar and Nail.
Occurences of magnesite have also been reported from Jhiroli, Pagankhol, Ariapani, Bhurgaon, Chandgdog, Boragar, Gahar Rithait, Satislang, Dhadiari Jakhera Tachhiri, Tanga Duari, in Chamoli district. These have been found to have a purity of 45- 45 percent, over a 2 km belt.
Small reserves are found in the Sabar Kantha, Junagarh and Banaskantha districts of Guajrat.
Talc magnesite rocks carrying stringers of magnesite occur on Pathar Pahar hill near Bitardari, 11 kms from Jamshedpur in Jharkhand, Kurnool district of Andhra Pradesh.
Two quite different minerals are included under this name; one, a variety of amphibole, resembling tremolite and the other, more important, a fibrous variety of serpentine (chrysotile). Both possess physical properties that make them valuable as commercial products. Asbestos (amphibole) occurs in pockets or small masses or veins in altered basic igneous rocks and in gneissic and schistose rocks.
The chrysotile variety, which supplies 80 per cent of the asbestos of commerce, forms veins in serpentine, and occurs in altered serpentinised basic and ultrabasic igneous rocks. Asbestos has found a wonderful variety of uses in the industrial world of today.
It is a naturally occurring silky fibrous material; but unlike other fibres, it is uninflammable and, therefore, invaluable in the manufacture of fire-proof, cloth, rope, paper, millboard, sheeting, belt, paint, and in the making of fire-proof safes, insulators, lubricants, felts, etc.
It is also used in making aprons, gloves, curtains, brake-linings in automobile and like industries and insulating mats. Mixed with magnesia, it is used for making ‘magnesia bricks’ used for heat insulation. Asbestos cement sheets are used for roofing. When asbestos is brittle, it is made into filter pads for filtering acids, organic liquids and other chemicals.
Production and Distribution:
Known in Telugu as Ratinara, asbestos of best quality is found in Pulivendla taluk of Cuddapah district. Here excellent chrysotile asbestos occurs at the contact of a bed of Cuddapah limestones with a dolerite sill. There are several occurrences between Chitravati and Papaghani rivers. The 15 kms long zone between Lopatanuthula and Brahmanapalle is the most promising.
Silky chrysotile, a commercial variety of asbestos has been recorded from the rocks in the Naga Hills, especially between Puchimi and Kurami in Tezu valley near Manyung River, between Namyung and Taap (or Tepe) river, and near Gedu River.
Asbestos occurs in over a hundred localities in Singhbhum district; of these the deposits in Seraikela chromite bearing area and Dhalbhumgarh areas and those in the Dalama ranges are important.
The possible reserves of asbestos in 32 localities so far estimated are of the order of 355,000 tonnes, down to depths varying from 6 to 30 m. Much of the Seraikela region of Singhbhum, which is of the actinolite variety, however, does not possess that softness or flexibility of fibre on which its industrial application depends.
The few occurrences that are found in the State are in the Narayanpur valley in Sabarkantha district.
Asbestos occurs in thin veins in the limestone near Bachai in Narsinghpur district; there is a possibility of finding workable veins in the neighbourhood. Asbestos also occurs in Jhabua district.
The main deposits occur in Hassan district. Asbestos in this area is of the brittle, amphibole type. Chrysotile variety of asbestos is known to occur in Mysore district.
Small occurrences of fibrous asbestos are reported in the magnesite area near Salem. These are capable of development for manufacture of asbestos cement if sorting and grading of fibre is carried out accurately the brittle variety of asbestos occurs in the magnesite area of Valiyapatti south of Namakkal in Salem district. Occurrences are also known in Nilgiri and Coimbatore district.
Important occurrences are known near Khewara and Rihabdeo in Udaipur district, Jakol and Khymaru in Dungarpur district and Alwar and Kishangarh districts.
Occurrences are reported in Mirzapur district and at Jalai and Kanddhara in Garhwal district.
Barytes occurs in the form of veins and as beds in shales. The rather uncommon heavy mineral barytes is the sulphate of harium.
Its uses are as a pigment for mixing with white lead, as a flux in the smelting of iron and manganese, in paper manufacture, in pottery glazes, etc. The whiter and better quality barytes is used in the local manufacture of paints (lithophone); the coloured variety is used in making heavy drilling mud by the oil companies. It is also used in the manufacture of textiles, rubber linoleum, gramophone records and printing ink.
Barytes is calcined with carbon and the product is used in the manufacture of barium salts which have numerous uses known as ‘calcine’ in industry and medicine. For instance, barium chloride, an important salt of barium, is used in water softening and in leather industry. Barium metal is utilized in electronic vacuum equipment.
Production and Distribution:
The in situ reserves of barytes are 85 million tonnes. The Mangampet deposit occurring in Cuddapah district (Andhra Pradesh) is the single largest deposit in the world. Minor occurrences of barytes are located in Rajasthan, West Bengal, Chhattisgarh, Madhya Pradesh, Tamil Nadu, Maharashtra, Uttar Pradesh, Jharkhand, Himachal Pradesh and Karnataka.
There are two varieties, viz. (i) snow-white, and (ii) buff-coloured (stained). The latter can be improved by appropriate treatment. It is found in Cuddapah, Anantapur, Kurnool, Krishna, Nellore, Prakasam and Khammamett districts. It has been estimated that Cuddapah district alone may contain 65.714 million tonnes of barytes of all grades down to a depth of 30 m.
Barytes occurs at Kolpotke in Singhbhum district and in a few isolated localities in Ranchi district. The occurrences near Kolpotke appear to be promising for commercial exploitation. Reserve of barytes has also been calculated from Palamau district.
The deposits occur in the form of veins and pockets in limestone south-east of Kanti and other localities in Sirmur district. Here the mineral is white, fine-grained and, for the greater part, appears to be very pure.
The estimated reserves are of the order of 13,900 tonnes. This deposit however, is remote from the nearest railway station, Jagadhri (Yamuna Nagar). Barytes is also reported near Rajpur, Khajjar and Tatyana.
Barytes has been reported from Chittradurg district of Karnataka where the reserve has been estimated at 9,105 tonnes.
Barytes occurs as veins in copper lode at Sleemanabad in Jabalpur district and near Gain and Rehti in dewas district. Barytes has also been reported from Sidhi, Dhar, Shivpuri and Tikamgarh districts.
About 38,045 tonnes of reserves of barytes has been reported from Chandrapur district in the state.
Numerous veins of barytes occur in North Arcot district. The mineral also occurs associated with celestite in a small area in Tiruchirapalli district. The amount is, however, too small to be commercially important. The mineral is also reported at Kunichchi in Coimbatore, and in Ramanathpuram district.
Barytes occurs at several localities in Alwar district, Hathori in Bharatpur, Bhilwara, Bundi, Pali, Sikar and Udaipur districts.
A reserve of 20,000 tonnes has been estimated from Dehradun district of Uttarakhand. On the whole, barytes occurs in sufficient quantities, but, with a few exceptions, the deposits were not worked till lately because of the absence of any demand for the mineral. The yearly output of recent years has risen to 211,726 tonnes valued at Rs 42 millions.
Continued to be the principal producer accounting for 98 per cent production in 1986. The all-India recoverable reserves of barytes are placed at 71 million tonnes. The reserves are located mostly in Mangampet taluk, Cuddapah district, Andhra Pradesh.
The increasing consumption is attributed mainly to the increased oil well drilling industry, the main consumer of barytes in India. Chemical industry is the next important barytes consuming industry using it for manufacturing barium chemicals such as barium carbonate, chloride etc. Other barytes consuming industry like paint, asbestos products, glass, and rubber, abrasive and ceramic accounted for about 5 per cent consumption in 1986.
Borax occurs as a precipitate from the hot springs of the Puga valley, Ladakh, in association with some sulphur deposits.’ It is of use in the manufacture of superior grades of glass, artificial gems, soaps, varnishes and in soldering and enamelling.
Like the nitre, alum and similar trades, the borax trade, which was formerly a large and remunerative one, has seriously declined, owing to the discovery of large deposits of calcium borate in the USA from which the compound is now synthetically prepared. The large resources of Puga were being projected to be refined locally for transport by air to industrial centres in India. Imports are made from Turkey, U.S.A and other countries.
Corundum is an original constituent of a number of igneous rocks of acid or basic composition, whether plutonic or volcanic. It generally occurs in masses, crystals, or irregular grains in pegmatites, granites, etc.
The presence of corundum under such conditions is regarded as due to an excess of the base A1203 in the original magma, over and above its proper portion to form the original varieties of aluminous silicates. In these instances, corundum occurs as an original constituent of the magma, but the mineral also occurs, in many cases as a secondary product in the zones of contact-metamorphism around plutonic intrusions.
Mostly corundum occurs in situ in the coarse-grained gneisses, in small round grains or in large crystals measuring several centimetres in size. Corundum, is next to diamond in hardness; it is widely used in the manufacture of abrasive, a common example of which is the corundum powder-coated wheel of the knife-sharpener. Finely ground corundum blended with clay has been used for making refractory crucibles capable of standing high temperature.
As an abrasive, corundum now has many rivals in such artificial products as carborundum, alundum, etc. Carborundum is used in the form of hones, wheels, powder, etc. by the lapidaries for cutting and polishing gems, glass, etc. Emery is an impure variety of corundum, mixed with iron ores and adulterated with spinel, garnet, etc. The abrading power of emery is much less than that of corundum, while that of corundum in general is far below that of its crystalized variety sapphire.
Production and Distribution:
The area around Punighi in Hindupur taluk is reported to have yielded earlier large quantities of corundum for export. It is also available in Anantapur, in Kalyandrug and in Dharmavaram taluks. It also occurs near around Shankara mica mine, near Griddalur in Nellore district. The area supplies the requirements of the leading abrasive factory at Chennai. It is associated with syenite and ultra basic rocks.
Corundum occurs in association with sillimanite in Sonapahar in Khasi hills, an area not yet fully investigated. Corundum is believed to occur also below the alluvial tracts in Sonapahar area. Deposits containing several tonnes may also be traced in Raindu river valley near the border between Garo and Khasi hills.
Corundum deposits are found in Singhbhum district.
Corundum is reported at a place about 1.6 kms from Paniari and in Morena district. Corundum of fairly good quality occurs in the corundum-sillimanite rocks about 800 m south-east of Pipra in Sidhi district, where pebbles of corundum are also recovered from the river bed. Small occurrences of corundum have been noted in Bastar district. Mainly it occurs in pegmatites-.
There is a large area of corundiferous rocks covering some parts of Tiruchirapalli, Salem and Coimbatore. In Dharmapuri taluk of Salem district, Corundum is found in a track 64 kms long and 1.58 kms wide. Corundum has also been mined for over two centuries in Sittampundi area in Namakkal along a 16 kms belt with an average width of over 1.5 kms. Mostly the corundum occurs in situ in the coarse-grained gneisses, in small round grains or in large crystals measuring several centimetres in size.
India’s large resources of corundum are mostly concentrated in Karnataka State. It occurs mainly in pegmatites. Various grades of corundum, varying in colour as well, are found widely distributed here. In the Sringeri Jagir, small quantity of good ruby-corundum occurs. Large crystals of brown corundum have been found in places further south in the Ghat section. A number of deposits are found in Hassan district.
Common salt or Sodium Chloride contains 39.22% sodium and 60.88% chlorine. It is either mined from sea water or produced by solar evaporation from the brine in the lakes of inland drainage.
Salt is an essential-ingredient of food and an important raw material for chemical industry. In India nearly 52% of the total consumption of salt in the country is accounted for by edible uses; heavy chemicals namely caustic soda, chlorine and soda ash are produced from common salt. Sodium Sulphate which is used in paper, glass and textile industry is prepared commercially from the common salt.
The other important users include paper, textile, jute, oil refining, fish curing, ice manufacturing dyestuff, water softening, tanning, and steel and explosives industries upto 12% of the total production.
Sources of Salt:
There are three sources of production of this useful material in India: (1) Sea water along the coast of the Peninsula; (2) brinesprings, wells and salt-lakes of the arid tracts, as of Rajasthan and Uttar Pradesh; (3) rock-salt deposit contained in Kachchh and in Mandi region (H.P.). Salt is one of the most common substances of use in daily life and is indispensable for several modem industries.
Assam, Nagaland and Manipur:
Although salt- lakes are common in the Barail rocks, no substantial deposits have yet been recorded in them. The climate of north eastern region is too moist to allow the formation of any superficial saline efflorescence.
At present salt is derived (and locally used) from the brine wells (known as ‘Pung’) fairly common in the Naga Hills. Brine springs also occur in Cachar district in various places and salt was formerly prepared in the Sadia and Jorhat areas in early days. The salt lakes and other local sources of salt of Assam require furter Investigation.
Most of the salt in Gujarat is produced by direct solar evaporation of sea water. An appreciable quantity of salt is also derived from subterranean brine in the Little Rann of Kachchh. The important salt producing centres are: Rajkot district; Jamnagar district: near Porbandar and Mongrol; Surat district; Bhavnagar Zalawad districts. Mithapur, Dharsana, Chharvada, Okha and Valsad.
Some millions of tonnes of pure rock-salt, produced by evaporation of sea water in enclosed basins, occur bedded in the sands of the Rann of Kachchh Kharaghoda and Dhrangadhra in little Rann of Kachchh produce large quantities from subterranean brine.
On the east coast Tamil Nadu is the largest producer of salt contributing nearly 18% to the national output annually. Chennai and Tuticorin have emerged as the largest centres of salt production from sea water next only to Gujarat.
The rock-salt deposits of Mandi are in a zone of limestone, shales and sandstones. Salt beds of considerable size occur here. Crystalline salt is occasionally met with. The average annual production from Mandi mines is fluctuating; in some years it had reached 4,470 tonnes. Mining of crystalline salt is done only in the Mandi mines of H.P.
Salt is manufactured at Shiroda in Ratnagiri district, in Kolaba district, in Thane district and Bombay. Average yearly production figure has been 492,000 tonnes. Bhandup, Uran and Bhayandar near Mumbai are large centres of production in Maharashtra.
Punjab and Surrounding Areas:
The groundwater is saline in parts of Sultnpur Mahal in the Gurgaon district and in Rohtak district. Salt extraction from this water has been under consideration.
Considerable quantities of common salt are prepared from brine. The important areas of production are the salt-lakes of Sambhar in Jaipur division, and Lonkarasar in the Bikaner division. The salinity of the lakes in this area of internal drainage has for long, been a matter of conjecture as to whether it is of local origin, or is due to constant dropping of wind-borne salt as dust from the seacoast or from the Rann of Kachchh.
Of the salt-lakes of Rajasthan, the Sambhar Lake is the most noteworthy. It has an area of 233 sq.kms when full during the monsoon, when the depth of the water is about 1.2 m. For the rest of the year it is dry, the surface being encrusted by a white, saliferous silt. (The cause of the salinity of the lake was ascribed to various circumstances, to former connection with the Gulf of Cambay, to brine springs, to chemical dissolution from the surrounding country, etc. But a series of experiments by Geological Survey authorities showed that the salt of the lake of Rajasthan is largely wind-borne.
About 132,000 tonnes of saline matter is calculated to be borne by the winds annually to these lake areas during the hot weather months. From a recent examination of the data regarding direction and strength of surface and upper winds in this region, however, it appears unlikely that a great proportion of salt could have been wind-borne from the Kachchh littoral.) The coastal areas of Goa, Karnataka and Kerala produce some salt from seabrine, though per ha production is relatively low because of higher rainfall and humidity conditions.
Other minerals occurring in significant quantities in India are bentonite (Rajasthan, Gujarat, Jharkhand and Jammu and Kashmir), corundum Karnataka, Andhra Pradesh, Rajasthan and Chhattisgarh), calcite (Andhra Pradesh, Rajasthan, Madhya Pradesh, Tamil Nadu, Haryana, Karnataka, Uttar Pradesh and Gujarat), fuller’s earth (Rajasthan, Jharkhand, Bihar, Andhra Pradesh, Tamil Nadu, Maharashtra, West Bengal and Karnataka), garnet (Tamil Nadu, Orissa, Andhra Pradesh, Rajasthan and Kerala), pyrites (Jharkhand, Rajasthan, Karnataka, Himachal Pradesh and Andhra Pradesh), steatite (Rajasthan, Uttar Pradesh, Kerala, Maharashtra and Madhya Pradesh), wallastonite (Rajasthan and Gujarat), zircon (beach sand of Kerala, Tamil Nadu, Andhra Pradesh and Orissa) and quartz and silica minerals are widespread and occur in nearly all states. Besides, the country has vast marble, slate and sandstone.
Granite is mainly mined in Tamil Nadu, Karnataka, Andhra Pradesh and Rajasthan; marble in Rajasthan, Gujarat and Uttar Pradesh; slate in Chhattisgarh, Madhya Pradesh, Haryana and Andhra Pradesh and sandstone in Rajasthan.