In Assam, mining is at present concentrated mainly
to four industrial minerals, namely, coal, oil and gas, limestone and
sillimanite. The history of coal mining in Assam goes back to the year
1834 when extraction of this mineral on a small scale was being carried
out at Cherapunji in upper Assam.
Coal was first mined in 1840 near Jaipur
by the Assam Tea Co. But the most important phase in the development of
the coal mining industry in Assam was the incorporation of the Assam Railway
and Trading Co. in 1882 for the exploitation of the upper Assam coal.
The most important coal mines in Assam are situated in the Ledo and Jaipur
areas of upper Assam. In the Mikir hills, two small collieries
exist -one at Koilajan and other at Seelbhata. The coal mining activity
in the Khasi hills is mostly concentrated around the Laitryngew area.
In addition to these small collieries, three mines exist in the Khasi
hills. Messrs Thanginath colliery and the Mawsynram colliery are important
among them. A small coal mine has been developed at Nangwalbibra in the
west Darranggiri Coalfield in the Garo hills under the auspices of the
ASMDC, a state government under taking. Petroleum mining is an outstanding
feature of Assami's industrial landscape. Its exploration and development
in the state are carried out by the oil and natural gas commission, Oil
India Limited and Assam oil company. The discovery of the first oilfield,
the Digboy field, goes back to the year 1889. The outstanding work
of the BOC in upper Assam has culminated in the discovery of the Nakarkatiya
(1953)and Moran (1950) fields which are now developed by the OIL company.
Limestone mining in Assam is confined to surface quarrying. Regular mining
activities have been started since 1938 in Therriaghat area in Khasi Hills.
Sillimanite has been known to occur at Sonapahar since 1922. In addition
to these major minerals , minor minerals such as gravel, sand, building
stone and ballast are produced at present at various places in the state.