Guwahati: Assam has sought help from the Indian Space Research Organisation for satellite mapping of untapped minerals in the state.

According to sources in the state's mines and minerals department, Isro's help was sought for technical assistance for identification and exploration of mineral resources that remain untapped due to lack of better technology for proper mapping.

"The revenue generated from mineral resources is one of the major sources of income for the state government. But this has come down as the present reserves in our state have reached saturation. So the department has decided to carry out proper mapping of new reserves of crude oil, natural gas, limestone, iron ore, granite and others. However, the conventional method of mapping which we follow is not sufficient for us. That is why the department has approached Isro for helping us conduct satellite imagery mapping and use of GIS software for better survey," a source said.

The directorate of geology and mining earned revenue of Rs 1826.98 crore in 2013-14, which came down to Rs 1657.34 crore in 2016-17 and Rs 1349.25 crore till December.

It has engaged agencies such as Oil India Ltd, Oil and Natural Gas Corporation, Assam Mineral Development Corporation, Coal India Ltd, Cement Corporation of India and some private companies for exploration of crude oil, natural gas, coal and limestone.

The reserves are leased out for a period between 15 to 50 years for exploration of the minerals and royalties paid to the state government.

Assam has crude oil and natural gas in Sivasagar, Jorhat, Golaghat, Cachar, Karimganj, Tinsukia and Dibrugarh districts.

While coal is found mainly in Tinsukia, Dibrugarh and Karbi Anglong, limestone is found in Karbi Anglong and Dima Hasao districts. Karbi Anglong, Kamrup and Goalpara have granites.

The department has found possible reserves of iron ore in Dhubri and Goalpara districts. Nagaon district may have glass sand reserves.