Mineralogical characteristics and mineral economics of Sanu and Gotan SMS grade limestone deposits of Rajasthan

Two large, chemically similar, SMS grade limestone deposits occur in Sanu area of Jaisalmer and Gotan area of Nagaur, Rajasthan. The Sanu deposit belongs to Khuiala Formation of Tertiary sequence of lower Eocene age, while Gotan deposit belongs to Bilara Group of Marwar Supergroup of late Neoproterozoic to early Cambrian. These deposits are being developed and utilised as flux in the steel plants of India. The Sanu limestone of Jaisalmer is more suitable compared to Gotan and other limestone deposits of the country due to its superior and favourable physical properties. Mineralogically, it consists of fine-grained, sub-rounded to rounded grains of calcite mainly replacing tests of the larger foraminifera. While, the Gotan limestone is composed of fine to coarse-grained, angular to sub-rounded grains of calcite. In Sanu area, about 54% of the limestone produced is being generated as -30 mm grit during the process of sizing for SMS grade. This lower size of limestone is suitable for making cement but due to non-avaibility of rail transport facility from Sanu to Jaisalmer for a distance of about 60 km, it remains unutilised as mineral reject.