Non Metallic Mineral Deposits
   Introduction to Non-Metallic Minerals and Decorative Stones of Rajasthan

INTRODUCTION

The state of Rajasthan is blessed with a rich variety of metallic as well as industrial (non-metallic) minerals (including rocks). Many of theses are geologically unique deposits formed by varied genetic processes. Most of its Precambrian deposits have explicit metamorphic imprints on them. Sedimentation and secondary processes are dominant in younger deposits. These mineral resources play an important role in economic sustenance of the people of the sate and the country.

Metamorphism is, however, dominant process of mineral formation and “Ore-Body Creator” for metallic as well as non-metallic minerals. These resources have been mined for centuries, rather millennia. Lead-zinc mining and smelting in Rajasthan is the oldest in and the Makrana marble, as also bronze and steatite possibly from Rajasthan, have been used during the pre-historic Indus Valley Civilization (Mohanjo-daro). Extensive utilization of these resources has, however, commenced in this century, essentially to meet the demands of modern-day life and owing to development of mechanization and infrastructure facility. Climatically, Rajasthan has a vast stretch of desert and a fairly large area of rocky/hilly tract, ravines etc., which are classified as “wasteland”. These areas are not suitable for agriculture and forest activities. Minerals sector activity has therefore been playing significant role in sustenance of its populace. The state government has therefore laid priority and trust in exploration and development of its fairly vast mineral wealth for the “IXth Plan which will usher into the 21st century” and for the Xth Plan.

Geological Features of the Non-Metallic Mineral Resources

The geo-episodic history of Rajasthan is fairly well understood because of the exhaustive studies on the ore genesis, stratigraphy, geochronology, structure, tectonics metamorphism and sedimentation for the rocks of the state. These rocks represent varied lithologies–arenaceous, calcareous, argillaceous sediments, acid to ultramafic and alkaline plutonic to volcanic igneous and metamorphic rock, representing a fairly long period of geological history spanning ~ 3500 million years. The pre-Vindhyan rocks have undergone polyphase deformation and low to high-grade metamorphism. All these varied episode have generated a unique and rich variety of mineral resources that have attracted attention of researchers and entrepreneurs the world over.

Broadly, the mineral resources can be grouped into (% represents the share of national production): High-grade metamorphogenic deposits: Medium to low-grade metamorphogenic deposits: Medium to low-grade metamorphogenic deposits (marble 90%, talc, pyrophyllite 87%, asbestos 90%); Metasomatic; Skarn (wollastonite, 100%); Igneous: Pegmatitic; Sedimentary (limestone; sandstones 70%); Biogenic (rock phosphate 75%); Hydrothermal; Residual Concentration (clays 71%); Evaporation (gypsum 93%). Many of the deposits have polygenetic imprint on them.

The state of Rajasthan is endowed with geologically and economically unique industrial minerals and rocks. The uniqueness is global as well as national.

  • The minerals of international importance are: stromatolitic rock phosphate, serpentinite, talc and wollastonite.
  • While those of national significance are: amphibole asbestos, clays (ball -, bentonite, china-, fire-, fuller’s earth), calcite, dolomite, feldspar, fluorspar, garnet, gypsum, ocher, pyrophyllite, quartz salts, sandstones, limestones (cement-grade, chemical-grade, flaggy-, SMS-grade), granites, marble (white, pink, green, gray), slate.
  • Minor quantities of barite, brick earth, emerald, epidote garnet (semi-precious), graphite mica, and vermiculite are also produced.

Rock Phosphate:

The deposits of stromatolitic phosphorite, belonging to Aravalli Supergroup, are of greatest significant and attained international status. These deposits are located at Jhamarkotra, Kanpur, Kabaria-Ka-Guda, Dakankotra, Maton, Badgaon, Manoharpura, Siserma and Neemchmata around Udaipur, are hosted by dolomitic limestone which at times become cherty and silicified towards the top (Srivastava, 1983). Roy et al. (1988), have established tectonostratigraphy for this region. Super imposition of F2 and F4 folds on the limbs of a large F1 isoclinal fold and formation of domes and basins due to interference of F1 and F2 folds are important structural features of the Jhamarkotra deposits. The Phosphorite ore extends for about 16 km with an average width of 15 meters and exposed in blocks A to K. The stromatolitic phosphorite occurs as columnar, brecciated, stratiform, lenticular, and in minor quantities as secondary colloidal deposit (Pandya, 1984). The high-grade ore Jhamarkotra phosphorite contain P2O5 content between 30 to 35% are directly usable, however, low-grade ores are needed to be beneficiated before use. Besides rock phosphate deposits, apatite occurrence of Nawania, Kikawas (Udaipur district), Kerpura and Salwari (Sikar district), phosphorite of Birmania and Fatehgarh (Jaisalmer district), Achrol (Jaipur district), Aduka and Avani (Alwar district), Sallopat and Ram-Ka-Munna (Banswara district) and Jaoda (Chittaurgarh district), occur in different lithological formations varying in age from Precambrian to Tertiary. The phosphate ore reserves in Rajasthan are estimated to be around 74 million tones.

Talc and Soapstone:

Talc, steatite, soapstone deposits of Rajasthan are located in Udaipur, Bhilwara, Dungarpur, Banswara, Sawaimadhopur, Pali and Jaipur districts of Rajasthan. They are associated with either dolomites or ultramafic rocks. Those associated with dolomites are of better quality and larger in size. The talc-soapstone deposits of Udaipur-Dungarpur- Rajsamand districts occurring both in dolomites and ultramafic rocks, occurs as thin bands, lenses or pockets. Major deposits are associated with dolomites belonging to Aravalli Supergroup in the four belts namely- (1) Oda-Devpura-Dangri-Natharia-Ki-Pal belt, (2) Ushan-Kagamdar-Jagat-Rabcha-Oden Patli belt, (3) Salumbar-Band-Sanjela-Lolagarh-Padla-Devla-Jagpura belt and (4) Kavita-Lakhawali-Parava-Rama Patli belt. Talc-Soapstone deposits of Undithal-Udarlotala-Khakar-Jharol-Dhandawali belt and Rishabadev-Kagdar-Bicchiwara-Sabla-Sisso-Kalayanpur belt are associated with metamorphosed ultramafic rocks of Jharol group of Aravalli Supergroup.

Soapstone deposits of Bhilwara district constitute talc deposits of Ghevria, Chainpura, Vagwara and Jahazpur region belong to dolomitic limestones of Bhilwara Supergroup. Talc-Soapstone deposits of Jaipur-Dausa districts extend for about 35 km in length. These deposits occur as thin bands, lenses and pocket in dolomite of Delhi Supergroup. Pyrophyllite deposits of Karoli – Sawaimadhopur districts occur in quartzite of Delhi Supergroup. They are located at Douta, Kamalpura, Ranjeli, Garni, Pura and Marsh villages along a belt of about 10km. Pyrophyllite deposits also occur in Udaipur and Rajsamand districts in two belts, Debari- Gudali- Negaria-Nathuwas belt and Bari – Madar – Rama belt. The first belt that runs fro 40 km and second for 10-12 km in length are located at the contact of the Archean and Aravalli Supergroup rocks. The host rocks for pyrophyllite are quartzites and granitic gneisses.

Wollastonite:

Major deposits of wollastonite are found in Sirohi, Udaipur, Dungarpur and Ajmer districts of Rajasthan. A rich wollastonite deposit has formed in calcic exoskarn of Belka and Khera Tarla Pahar (N24° 46’: E 73° 10’) in Sirohi and Udaipur district. The estimated reserve of 9887000 tonnes is being mined by M/s Wolkem Industries limited. The open cast mine produced 134763 tonnes of wollastonite in the year 2001-2002. This makes it the largest wollastonite resource production centre in India and second in the World i.e. next to China. About 90% production is utilized in India and rest is exported (57071 t in 2001-2002). Additionally, a large producction of calcite is also obtained from this area

Minor occurrences of Wollastonite are found in Ajmer and Dungarpur districts that produce 200-300 tonnes of wollastonite per year.

Wollastonite Bearing Skarn Deposits of Gujarat:

Besides Rajasthan there are deposit of wollastonite in Godha Taluka (Palampur district) and Chhota Udaipur Taluka (Baroda district) in Gujarat. The estimated possible reserve is around 1.5 million tonnes.

Both the above deposits of Rajasthan and Gujarat fall in the South Delhi Fold Belt (SDFB) and have been included in Sirohi belt. Geological Survey of India (Gupta et.al.,1981) have placed them at top of the Delhi Supergroup and the syntectonic intrusion of Erinpura granite resulted in the formation of skarn deposits.

The crustal deformation and associated thermal regime caused large-scale anatexis and emplacement of a number of granite plutons (Erinpura Granite and its equivalents) along and adjacent to the SDFB at about 900 m. a. Some of these plutons are responsible for skarn mineral deposits as well as for Sn-W-Mo mineralization.

Near the southern extremity of the SDFB the regional metamorphism has been over printed by thermal metamorphism (syntectonic to Erinpura granite). Siliceous marble developed diopside- forsterite assemblages and amphibole developed Hb + Labradorite + diopside assemblages. The late phase enriched the Sn and W is represented by the Balda Granite in Sirohi district.

Wollastonite Bearing Skarn Deposits Of South India:

Two small deposits of wollastonite are reported in Dharmapuri and Tirunelvelli districts in Tamilnadu.

Amphibole asbestos:

The occurrence of amphibole asbestos is of great significance in national context due to very limited reserves of chrysotile asbestos in India, the latter is commercially procured in limited quantities from Andhra Pradesh with known occurrences in Karnataka, Madhya Pradesh and Uttar Pradesh. Asbestos deposits of Rajasthan are located in Ajmer, Udaipur, Rajsamand, Pali, Dungarpur and Alwar districts. They as metamorphosed products of ultramafic rocks, hich are intrusive in the rocks of Aravalli and Delhi Supergroups, along the prominent lineaments.

Clays:

  1. Kaoline and ball clay: These resources are mainly confined to sediments of Precambrian, Jurrassic and Eocene period, and are located in Bhilwara, Chittorgarh, Sawaimadhopur, Nagaur, Barmer, Jaisalmer, Pali, Kota, Jaipur and Sikar districts.
  2. Fire Clay: The fire clay deposits of Rajasthan mainly occur in Bikaner, Alwar, Sawaimadhopur, Jhunjhunu and Barmer districts in rocks of Delhi Supergroup and Tertiary period. Due to high temperature resistant character these clays are used in manufacture of high temperature resistance bricks for steel industry, ceramic industry cement industry and thermal power plants.
  3. Fuller’s Earth: The fuller’s earth deposits of Rajasthan occur in Barmer, Jaisalmer, Bikaner and Nagaur districts. Its beds up to 13 meters thick occur below the Kapurdi formations. It also occurs above and below the lignite seams. In Jaisalmer district the fuller’s earth occurs below the limestone beds. This mineral is known in the industry as bleaching clay of non-swelling type that absorbs oily substances and is used in several industries including purification of vegetable oils and petroleum.
  4. Bentonite: The bentonite deposits of Rajasthan are located in Barmer, Jaisalmer, Sawaimadhopur and Jhalawar districts. The high quality deposits occur in Barmer district only. The bentonite deposits lie above the Lathi Sandstone and Barmer Sandstone of Jurrassic and cretaceous age respectively. The bentonite deposits are also associated with Kapurdi formation of Eocene age and as an alteration product of Malani volcanics. It is bleaching clay of both swelling and non- swelling type constituted of montmorillonite. Its major uses are for grouting work in dams and other foundation works, petroleum drilling, cosmetics, insecticides, paint and pharmaceutical industries, bleaching of oils, sugar and petroleum.

Calcite:

The calcite deposit of Rajasthan mainly occur Sirohi, Udaipur, Pali, Sikar, Jhunjhunu, Alwar, Jaipur and Ajmer districts. The largest deposits are those of Sirohi district where it occurs in association with the wollastonite in skarns of Belka Pahar region. The calcite occurs in center part of the lenses spread over 300 meters long and 45 meters wide deposits. The calcite also occurs as lenses in crystalline limestones and calc- silicate rocks of Delhi Supergroup in Udaipur and Sirohi districts. The calcite is mainly used in rubber, textile, plastic paint and ceramic industries.

Feldspar:

Feldspars, quartz, mica beryl and associated minerals occur in complex pegmatites. Simple pegmatites contain only quartz and feldspar with or without mica and it is these pegmatites which produce the maximum quantity of feldspars. Feldspar deposits of Rajasthan occur in Ajmer, Rajsamansd, Jaipur, Tonk, Udaipur, Bhilwara, Pali, Sirohi, Alwar, Jhunjhunu and Sikar districts. The mineral has its maximum use in ceramic industry, and also used in glass industry, high temperature resistant refractory, abrasives and electrode industry.

Fluorspar:

The deposits of fluorspar are found in Dungarpur and Jalore districts with minor occurrences in Sirohi, Alwar, Bhilwara, Banswara, Jaipur, Barmer and Sikar districts. The mineral is hosted in different rocks of the Precambrian BGC formations viz., mylonites, granite gneisses and quartzites and Malani pyroclastic rocks. The fluorspar mineralization is outcome of hydrothermal fluids of varied physico-chemical parameters. The mineral has its major use in steel metallurgy, manufacture of artificial cryolite, production of hydrofluoric acid, as a flux in and opalescent glasses, melting of metals, aluminum industry and as chloro-fluoro-carbon refrigerant.

Garnet:

Garnets are mainly used as an abrasive and also as semiprecious gem mineral. It is product of regional and contact metamorphism and also found to occur in the form of placer deposits. Garnet deposits of Rajasthan occur in Tonk, Ajmer and Bhilwara districts in pegmatites and schist of Aravallii and Delhi Supergroups.

Gypsum:
In Rajasthan gypsum deposits occur in rocks or tertiary period, and are considered to have by evaporation process . About 80% of Indian gypsum deposits are located in Jaisalmer, Barmer, Bikaner, Jodhpur, Nagur, Churu and Ganganagar districts of Rajasthan. Gypsum has its major use in the manufacture of cement, ammonium sulfate (fertilizer) and plaster of Paris. It is also used insecticides, paper and paint industries.

Siliceous earth:

It is mainly composed of silica and looks like clay and chalk. The composition of siliceous earth in Rajasthan varies between 69-81 % silica, 4-12% alumina and 3-10% water with low contents of CaO, MgO and FeO and found to occur in rocks of cretaceous tertiary periods. It is mainly used as filler and filter, heat and sound resistant material and in ceramic industry. Filtration and cleaning of vegetable oils and animal fats and manufactures of medicines are other uses of this mineral. Rajasthan is the only state of India that produces this mineral.

Ochre:

The Ochres are oxides of iron found in rocks of all the geological time period. The ocherous clays are formed as residual concentration due to alteration if igneous, sedimentary and metamorphic rocks. Commercially they are known as red ochre, yellow ochre, green ochre, and amber-brown- yellow ochre. Ochres are used in the colour, paper industry, paint industry, manufacture of red oxide paint, cement industry, fertilizer and foundry industry. The ochre deposits are found in Chittorgarh, Udaipur, Bhilwara, Jaisalmer, Bikaner, Jodhpur and Jhunjhunu districts of Rajasthan.

Quartz:

Quartz is main raw material for ceramic, pottery, foundry and glass industry. Quartz occurs either in sample pegmatite along with feldspar or in complex pegmatites with feldspar, mica, beryl, tourmaline, apatite, lithium mica, fluorite and other minerals. It also occurs as veins in different rocks types of varying ages, resulting from late hydrothermal crystallization.

Salts:

Halite is used in several chemical industries besides its use in our daily meals. Manufacture of soda caustic soda, metal smelting, cleaning of leather, manufacture of medicines, ceramic industry and acid industry. Rajasthan produces common salt (halite) from lakes of Sambhar, Didwana and Kuchaman in Nagaur district, Pachbhadra Lake of Barmer district and Nanwa Lake of Bikaner district. The potash salt minerals occur at the Nanwa Lake of Bikaner district. The potash salt minerals occur at the depth varying from 385 to 965 in Nagaur, Churu, Ganganagar and Bikaner districts. Major potash minerals sylvite (KCI) and langbeinite [K2 Mg2 (SiO4)] are used in fertilizer industry. They are also used in chemical industries and manufacture of explosives. The generally accepted views on the origin of salt deposits is by evaporation process, however considers their formation due to prolonged aridity in tectonically controlled depressions.

Barite:

The deposits of barite are located in Alwar, Udaipur, Ajmer, Bahratpur, Sikar, Chittaurgarh, Jalore, Rajsamand, Bundi and Pali districts in rocks belonging to Bhilwar, Aravalli, Delhi, Vindhyan Supergroups as well asin Malalni Suite of igneous. Barite occurs in a variety of host rocks in the form of fracture filling, breccia filling, replacement and residual concentration type. It is also used in paints, and chemical industry, manufacture of barium and as filler in rubber, textile, leather, glass and paper industries.

Emerald:

It occurs sporadically in altered ultramafic rocks in close association of biotite schist, actinolite schist, talc-schist. Emerald develops wherever pegmatites intrude at the contact of schist and altered ultramafic rocks. Well-known occurrences are at Rajgarh, Bubani in Ajmer district and Kaliguman, Gamgurha and Tikhi areas in Rajsamand district. The emerald belt strikes NNE-SSW and runs for about 200km. and was important source of valuable gem for centuries. At present, however, these localities do not produce any emerald.

Graphite:

The graphite occurs in minor quantities in Precambrian rocks of Banswara, Ajmer, Udaipur and Alwar districts. Geologically, graphite occurs in rocks of Aravalli and Delhi Supergroups. Graphite has its application in foundry works and manufacture of crucibles because of its high temperature melting and resistant character.

Limestone:

The limestone deposition takes place both by organic and inorganic processes. Major limestone deposits of Rajasthan have formed during the Precambrian (Aravalli, Delhi, Vindhyan, Marwar Supergroups) and Jurassic as well as in Eocene periods. It has application in iron and steel industry, construction works, cement, paper, glass, sugar, textile, chemical and leather industry. It is also utilized as a flux in copper and lead smelters. The limestone deposits occur in Udaipur, Dungarpur, Banswara, Rajsamand, Sirohi, Pali, Ajmer, Jaipur, Sikar, Jhunjhunu and Alwar districts. The limestone of Bhilwara and Aravalli Supergroups are of cement and chemical grade. The Vindhyan Supergroup has large deposits of cement grade limestones, which support cement plants in Chittorgarh, Bhilwara, Kota, Bundi, Sawaimadhopur and Karauli districts The Marwar Supergroup has occurrences of steel, cement and flux grade limestones in addition, chemical grade limestone is also present. The Jurassic and Eocene limestones of western Rajasthan are of steel grade.

Dolomite:

Dolomite is both sedimentary as well as metamorphic in origin. It is mainly utilized as a flux, cement, fertilizers, rubber and paint industries. The dolomite deposits occur in Ajmer, Bhilwara, Rajsamand, Banswara, Alwar, Jodhpur and Jaipur districts of Rajasthan. Geologically, dolomite occurs in Bhilwara, Aravalli, Delhi and Vindhyan Supergroups in Rajasthan.

Sandstone:

The sandstone deposits of Rajasthan belong to Vindhyan Supergroup and Marwar Supergroup. At places the sandstone deposits of Tertiary period are also present. They are shallow water sedimentary rocks. The vindhyan sandstone deposits are located in Chittorgarh, Bhilwara, kota, Bundi, Sawaimdhopur, Karauli and Dholpur districts while those of Marwar Supergroup occur in Jodhpur, Nagaur and Bikaner district. Acid proof sandstone deposits of Khimach located in Jhalawar district are used in chemical industries. Cream colored sandstone of Khatu is popular for carving works.

Granites:

There are huge deposits of granites in Rajasthan in the Aravalli Mountain Range as well as in western Rajasthan. Granites of varying ages (Precambrian) are of igneous and metamorphic in origin; the former is generally used to make slabs and tiles for decorative purposes in building constructions. The major deposits of granite are located in Jalore, Sirohi, Barmer, Pali, Sikar, Tonk, Jaipur, Ajmer, Jhunjhunu, Bhilwara, Rajsamand, Udaipur, Duingarpur and Banswara districts. Well-known trade names of granites are Jalore pink, Mokalsar green, Shivganj white, Chima pink, Bhilwara laharia and black etc.

Marble (White, Pink, Green and Gray):

Marble, sensu strict, is a metamorphic carbonate rock and compositionally classified as calcite, dolomitic, siliceous, ferruginous and impure marble. Calcitic marble is the best quality amongst the white marble. The term ‘marble’ is used here in a loose sense, which includes relatively softer rocks capable of taking good polish and suitable for decorative works. In this context marble shows different compositions and belongs to age range varying from the Precambrian to Jurassic. Marble occurrences in Rajasthan are located in Nagaur, Jaipur, Alwar, Ajmer, Rajsamand, Udaipur, Dungarpur, Banswara, Chittaugarh, Bhilwara, Sirohi, Pali, Jaisalmer, Jhunjhunu and Sikar districts, whose trade names are based on colour such as Makrana-white and Adaga (variegated), Babarmal pink, Kesariaji green, Rajsamand white, Bhainslana black, Selwara white & Adanga, Abu- Ambaji green, Banswara pink, Jaisalmer yellow, Andhipista, Mandlade brown etc. The state of Rajasthan contributes more than 90% of India’s production of marble. Although Makrana marble was known for its use in temples, palaces and historical monuments for several centuries, its use for common men started only when sawing, cutting and polishing techniques developed in late 1970s.

Serpentinite (the so-called green marble):

Serpentinite has deep green colour, and yields slabs, which generally take good polish, therefore it is mostly exported. Rajasthan contributes up to 90% of Indian production from a belt called Rikhabdev ( Rishabhadev or Kesariaji)- Masaron-ki-ovari-Dakchi belt in Udaipur and Dungarpur districts. The serpentinite is a product of hydrothermal metamorphism of Precambrian ultramafic rocks.

Slates, Schists and Phyllite:

Rocks of this category are used in roofing and decorative works. These are metamorphic argillaceous rocks belonging to the Precambrian period. In Rajasthan, shales and slates are mainly mined and processed into tiles in Mandon region of Alwar district and also in Tonk district. Slates and schist of white, red, pink, brown and other colours are mined in the above mentioned regions. The Aravalli and Delhi Supergroups have vast potential of slates, phyllites and schists rocks in Udaipur, Bhilwara, Pali, Rajsamand, Banswara and Dungarpur districts.

MINERAL RSOURCES UTILISATION AND ITS IMPACT

Humanity has utilized minerals for millennia and dependence on them is now total, as one can not imagine living the modern-day life with out the use of minerals. The mineral resource utilization has several impacts, out of which few ones are:

  1. mineral resources are non-renewable, finite assets,
  2. the per capita consumption of minerals is increasing rapidly
  3. mechanization and development of infrastructure has added to their rapid utilization
  4. micro-level environmental adjustments.

The mineral resources are not uniformly distributed on the surface of the earth; consequently, certain limited areas are blessed with mineral riches. Evaluation of land use pattern for the state of Rajasthan has revealed that the land use for mining, direct and indirect, is less than 1% of its total surface area. The mining activity has also resulted in certain environmental degradation, but the problem was unfortunately highly exaggerated during past decade and a panicky situation developed due to the biased attitude of people who should have taken a more informed perspective. Every human activity results in certain negative impacts. Mining of industrial minerals and rocks in Rajasthan has also caused micro-level impacts that can easily be handled. Because of the climatic handicap a very large section of state’s population depended on livestock rearing, a small section of the population had been migrating out of the state for its livelihood. Mining is not only changing but is reversing this pattern. Rajasthan is no longer a backward state of the Union that it was few decades back- mining activity has added considerably to this development. Therefore, the concern regarding deforestation and environmental degradation due to mining activity is unjustified.