Pegmatites As Decorative and Dimensional Stone Occurring in South-Central Rajasthan, India

Abstract

The Precambrian formations of south-central Rajasthan host the unique deposits of pegmatite popularly known as ‘Alaska white’. These deposits are located mainly in Jawaja and Rajgarh areas of Ajmer, Gangapur and Jahazpur areas of Bhilwara and Amet and Deogarh areas of Rajsamand districts, Rajasthan. Field and the mineralogical study indicate that these deposits represent a compact and massive-type of pegmatite composed mainly of microcline, quartz and muscovite with subordinate amounts of albite and tourmaline. These pegmatite deposits occur as rounded to sub-rounded lenticular bodies emplaced concordantly within the rock formations of Bhilwara and Delhi Supergroups. These deposits are being developed and utilized by open-cast, fully-mechanized block-benching methods of mining for their extensive use as decorative and dimensional stones. Nearly 90% of the recovered resource is being exported mainly to U.S.A. and China in the form of well-dressed blocks of suitable sizes.