Sillimanite is an important high alumina refractory. Its blocks are used in furnaces (of glass industry) which are subjected to very high temperatures. It is also used in the making of sparking plugs for automobiles, manufacture of bricks, refractory fitting for electrical appliances, and lutes for surface combustion.
The total recoverable reserves of sillimanite in the country are 51.6 million tones. Besides, conditional and prospective resources of 5.9 million tones and 0.8 million tons respectively of sillimanite are also estimated.
The total production of sillimanite was 4114 tons valued at Rs. 198,000 in 1951. It increased to 20,394 tons valued at Rs. 282.19 lakhs in 1992-93. Since then there has been gradual decline in the production of sillimanite so as to fall down to 8,528 tons in 1996-97. The production has observed slight recovery in the following years (15,492 tons in 2000-01). Table 17.XXXVII exhibits the trend in the growth of sillimanite production in the country.
More than 88 per cent of the total production of sillimanite of the country is provided by two states of Kerala (32.21%), and Orissa (55.87%).
Kerala-In Kerala the beach sands contain 5 to 6 per cent of sillimanite. Kozhikode, Palakkad, Ernakulam and Kottayam districts are the major producers.
Meghalaya-Earlier Meghalaya was the major producer of sillimanite in the country. According to Dr. J.A. Dunn the total estimated reserves are at 250,000 tonnes (up to a depth of 7 m). The mineral occurs in 21 scattered deposits in the vicinity of Sonapahar, Nongpur and Nongbain villages in the
Nongatoin area of Khasi Hills in Meghalaya. The (deposits possess 94.85 per cent sillimanite, 3.24pa cent corundum, 0.80 per cent haematite and 0.45pa cent ilmenite. The mineral occurs in the formal massive boulders and is worked out by the Assail Sillimanite Ltd.
Others-Sillimanite deposits also occur in Maharashtra (Nagpurand Bhandaradistricts); Madhya Pradesh-Chhattisgarh (Sidhi, Rewa and Bastardii F tricts); Bihar-Jharkhand (Gaya, Ranchi. Mungeram Singhbhum districts); Tamil Nadu (Coimbatort,T Tiruchchirappalli districts); Gujarat (Kaira district); Orissa (Mayurbhanj, Keonjhar and Sundargarh districts); and Rajasthan.
India exports some sillimanite to Japan, China, U.S.A., Germany, and Thailand. In 1993-94 the export amounted to 490 tons valued at Rs. 20 lakhs (cf. 2514 tones in 1968). There has been slight decline in the quantity of export in the recent I years.