The mineral wealth of the State is quite impressive with a large number of metallic and non metallic mineral occurrences. The mineral wealth includes limestone, dolomite, graphite, pyrite, lead, zinc, coal, oil & natural gas, etc. There are evidences of Gold extraction from the alluvium at the mouth of the SubansiriRiver.Distribution of mineral is explained below
Coal:
It occurs at two stratigraphic levels under different tectonic setting, one is Tertiary in age and the other is Gondwana. Unlike the Peninsular counterpart, the resources of coal in Arunachal are insignificant in the Gondwana Formations whereas sizeable resources occur in the Tertiary .
The bulk of the coal resources in Arunachal is located in the Namchik-Namphuk coalfield in Changlang district spread over an area of 35.5 km2, which is supposed to be the eastern extension of the adjacent Makum Coalfield.
Oil and Natural gas:
It is one of the most valuable resources and is available in Arunachal in Changlang district, particularly in Kumchai, Diyun and Kharsang area. Of these, the Kharsang Oilfield is supposed to be the continuation of the Digboi Oilfield. In addition, crude oil seepage is known since long in the fractured shale of Disang Formation near Nampong and in the Surma Group near Lungchong.
Dolomite:
Deposits of limestone/dolomite are found in different stratigraphic settings in different places, such as at Tidding in Lohit district; near Hunli in Dibang Valley district; near Pangin in East Siang district; and at Menga in Upper Subansiri district; and at Jamiri and Rupa in West Kamen district. The dolomite can be utilized as flux in steel industry, blast furnace, chemical industry and in agriculture. Similarly, the limestone can also be utilized in cement and chemical industries, and also could be used for lime burning and as chips in building material. It is worth mentioning here that a cement factory was started at Tezu in Lohit district to utilize the rich deposits of limestone at Tidding. This factory had a capacity of 30 tones/ day and started its commercial production in 1985, but it was closed down within a short period. A thorough investigation may indicate the reasons about the closure of the factory, which otherwise could generate a good revenue as the raw material is available in plenty.
Graphite:
It is associated with the mica schist and sericite quartzite and occurs in form of thin bands and lensoid bodies particularly in the rocks of Bomdila and Se La groups. About 50 m thick band of graphite is located near Did village on Zorum-Palin road and near Bopi on Tamen-Raga-Daporijo road in Lower Subansiri district. Other than these, some scanty deposits have also been observed associated with the chlorite schist near Abdullah Nala on Kimin-Ziro road, and a 70 m thick band of graphite schist containing flaky graphite has been located near Taliha in Upper Subansiri district
Lead and Zinc:
Some lead and zinc occurrences are reported from Shergaon area in West Kameng district. The reserves are yet to be estimated in the area, however, from the visual estimation and the analytical results a 20 m thick zone having 3-5% lead and zinc content has been inferred by the Geological Survey of India near Amritganga.
Ferro-Silicon Minerals:
The Ferro-silicon grade quartzite deposit is located in an area of about 25 km north of Kalaktang village of West Kameng district.
Clay
Small pockets of clay having moderate to good plasticity are associated with Siwalik sandstone, exposed in the foothill belt bordering the Brahmaputra Flood plain. A small reserve of 80,000 tones has been estimated in East Kamengdistrict.Though with the limited extent, the economic viability of the clay is to be ascertained, however, it may be suitable for use as pozzolamic material.
Other potential resources in Arunachal include mineral water and hot water sulphurous springs, which have been disseminated at number of places.
Quartzite :
Significant deposits of quartzite are also found at several stratigraphic horizons almost in all the main road sections of Arunachal. Of these significant exposures, which need attention for exploitation, are between Ziro-Tamen, Daporijo-Taliha, Dali-Basar, Bame-Along, Bame-Daporijo, Kaying-Tato, Pangin-Boleng, Roing-Myodia Pass, and Tezu-Tidding. Other than these, there are many other areas that need to be surveyed to locate the quartzite deposits of viable economic importance.
Granite/Granite Gneiss :
It is available in different stratigraphic levels in almost all the districts, except Changlang and Tirap. However, potential deposits viable for such purposes are exposed along Tenga-Bomdila, Dirang-Se La, around Tamen and Daporijo.
In addition, there a number of other economic minerals such as gold, cobalt, nickel, copper, magnetite-hematite (iron ore) and other platinoid group of metals, which are known to occur in the State. Although some scanty reports are available, it needs a thorough investigation for their economic viability.
Building material:
The State has plenty of the building material in form of marble, granite, volcanic rocks, such as gabbro, diorite, basalt, etc., quartzite, slate, etc. that may be utilized for making tiles and mosaic chips, which are in demand in modern urbanization. In addition, sand, concrete, boulders, etc., are also present, which are already being used and giving a good revenue to the State.
The State has sand, concrete, gravel, etc., in sufficient quantity. They are of ubiquitous nature and can be made use in local areas. The stone crushing industry may be another good opportunity of utilization of a vast quantity of boulders in the State. With the increase in the density of transportation, the road network is also going to be improved, as such concrete of uniform shape and size is required which can be obtained by crushing the boulders.