Meghalaya is a storehouse of economic minerals. The major minerals that are presently exploited are Coal, Limestone, Clay and Sillimanite. These minerals are utilised in several mineral-based industries in the country. Besides, Coal and Limestone are also exported to Bangladesh, earning a good amount of foreign exchange. The State earned a total revenue of Rs. 3980.32 lakh from mineral sector during 1997-98.

Mineral map of Meghalaya

Some prominent coalfields in the State are west Dadenggiri, Siju, Balpakram, Pyndengrei, Langrin, Mawlong-Shella, Laitryngew and Bapung. The total estimated inferred reserve of coal in Meghalaya is of the order of about 640 million tonnes, out of which, Garo Hills alone contains 359 million tonnes.

The total production of Coal in the State during 1997-98 was 32.34 lakh tonnes.

An extensive belt (approximately 200 Km. Long) of good quality Limestone (cement grade to chemical grade), having 3 (three) brands of Limestone, occurs along the southern border of Meghalaya. Some prominent Limestone deposits are Cherrapunjee, Mawlong-Ishamati, Komorrah, Shella, Borsora in Khasi Hills, Siju and Nangwalbibra in Garo Hills, Lumshnong, Sutnga, Nongkhlieh, Syndai and Lakadong in Jaintia Hills. Total inferred reserve of Limestone within the State has been estimated at about 5,000 million tonnes. The chemical analysis confirms its utility in the steel, fertiliser and chemical industries besides in the production of cement.

The existing cement plants, one at Cherrapunjee in Khasi Hills (Public Sector) and other at Damas in Garo Hills (Private Sector) have been using the Meghalaya Limestone. Besides these, Limestone of Meghalaya will also be utilised in the 2 (two) proposed cement plants, one at Garo Hills (1,000 TPD) and the other one at Jaintia Hills (1,200 TPD), both in the Public Sector.

The total production of Limestone in the State during 1997-98 was 3.95 lakh tonnes.

White Clay deposits are found to occur in various parts of the State. The sedimentary or Lithomargic clay occur in the Tertiary Formation, while Kaolin (China Clay) is associated with the Archaean gneissic rock. From physico-chemical test Kaolin is found to be suitable for the ceramic, paper and rubber industries. Fire Clay (reserve over 6 million tonnes) with refractory characteristics are found to occur in Garo Hills and are suitable for manufacture of Fire-bricks and Refractory industries.

Sedimentary white Clay or Lithomargic Clay is found in Cherrapunji and Mahadek in Khasi Hills, Larnai and Tongseng in Jaintia Hills and Nangwalbibra and Rongrengiri in Garo Hills. The mineral may be used in whiteware industry. A probable reserve of about 90 million tonnes of this Clay has been estimated.

Kaolin or China Clay occurs around Mawphlang, Smit and Laitlyngkot in Khasi Hills, Thadlaskein, Shangpung, Mulieh and Mynsngat in Jaintia Hills and Darugiri in Garo Hills. The probable reserve of Kaolin in Meghalaya estimated so far is of the order of 4.5 million tonnes.

One of the best Sillimanite deposits of the world is found in the Sonapahar region of West Khasi Hills. Geologically, these Sillimanite deposits occur in association with corundum, within the quartz- Sillimanite schist which form a broad band that can be traced discontinuously over the area. The high alumina-content of the rock makes this mineral a natural refractory mineral of great commercial value. The total inferred reserve of Sillimanite in Sonapahar and Mawpomblang is estimated at 0.045 million tonnes.

Nodules of Phospherite, a fertiliser mineral, occur at the base of the Kopili Shale of Eocene age in Meghalaya. A phosphate deposit is located in the Sung Valley at the border of Khasi and Jaintia Hills districts, besides, some Phosphatic nodules are also located in Rewak area of Garo Hills. The rock containing Phosphate in the Sung Valley is known as Apatite Magnetite rock which has 15% to 30% of Phosphate-content. The reserve of Phosphatic rock as estimated by Geological Survey of India is about 5 million tonnes.

Glass-Sand or Silica-Sand occurs in Laitryngew, Umstew and Kreit in Khasi Hills and Tura in Garo Hills. The sand contains a slightly high proportion of iron which is not suitable for the production of first grade glassware. However bottles or sheet glasses may be manufactured from these sands where colour is not the sole consideration. The Silica-Sand can also be utilised in the manufacture of sodium silicate. The total reserve of Glass-Sand in Meghalaya is of the order of 3 million tonnes. The Assam Glass Factory at Guwahati used this Glass-Sand and found it suitable for the purpose.

Deposits of multi-coloured Granite suitable for use as dimensional and decorative stones have been located in the area around Nongpoh, Mylliem and Mawkyrwat as well as in the area around Mendipathar - Songsak road. A possible reserve of about 25 million cubic metres of Granite deposits have been estimated by the Directorate of Mineral Resources at Nongpoh, Mawkyrwat and Mendipathar - Songsak.

Black Granite (Dolerite) suitable for making polished blocks and slabs are also found in eastern and northern part of West Garo Hills district. Jenjal and Hallidayganj appear to be two promising areas of Black Granite deposit in the State at present.

Both Quartz & Feldspar are components of ceramic industry. These minerals are found to occur side by side in Pegmatite Veins in several localities of Khasi and Garo Hills of Meghalaya. These minerals have been used in pottery industries in Meghalaya and Assam. Total indicated reserves of Quartz & Feldspar deposits in Meghalaya are estimated at 0.076 and 0.096 million tonnes respectively.

Gypsum, one of the ingredients in cement manufacture is reported to occur in Mohendraganj and Harigaon in West Garo Hills. It occurs as minute crystals in the gypsiferous shale. The concentration of Gypsum in shale is 0.07%. No detail works were carried out and no reserves were estimated so far, as the concentration of Gypsum in the host rock is uneconomic.

Geological and Geophysical investigations as carried out by Geological Survey of India in a Shear Zone from Tyrsad to Barapani in Khasi Hills could not indicate any rich zones of sulphide mineralisation, but established the occurrence of copper, zinc, nickel and cobalt , in the Shillong group of rocks and metadolerite of the area. At Umpyrtha of Khasi Hills, the polymetallic base metal mineralisation within the Archaean gneissic complex occurs discontinuously for about 5/6 kms. zone form Umpyrtha to Patharkhmah.

In the Umpyrtha block, the zones of polymetallic sulphide mineralisation indicates the presence of copper (1% to 1.5%) and zinc (2.25%) along with traces of molybdenum and tungsten.

Occurrence of Gold in a Shear Zone has been reported from Tyrsad, Khasi Hills. The Gold is associated with Arseno-Pyrite and Pyrite. The maximum thickness of gold-bearing rock is 2.90m recorded in a bore-hole. In the core samples, the gold-content is found of the order of 0.8 gram/tonne to 62 gram/tonne, which is not economically viable for extraction. Occurrence of traces of Gold has been reported from rocks around Tyrsad in Khasi Hills.

Uranium and some other radio-active minerals are found in different parts of the state. The Uranium deposit located at Domiasiat in West Khasi Hills district is of higher grade compared to a deposit presently been exploited in the country.

Banded-haematite quarzites are found in association with the gneissic complex at Aradonga, Athiabari and Nishangram areas of Meghalaya.