Minerals and Metals in Ancient India v2.c43.s3.t8.16

v2.c43.s3.t8.16

Mocha-stone, also known as dendritic or moss agate is a white or grey chalcedony, showing brown, red or black dendritic markings resembling trees and plants. These have been formed by the percolation of a solution containing iron or manganese through fine cracks of the stone, and the subsequent deposition of the colouring matter originally held in solution. The brown and red markings are caused by oxides of iron, and the black by oxide of manganese. Mocha-stone came from the neighbourhood of Mocha in Arbia, hence the name. Mocha could also be a corruption of moschas or moss-stone. It has been principally obtained from several places in India such as the Deccan traps, Rājkot, Kāthiāwār peninsula, the beds of Godāvarī, Narmadā and Jamunā etc. Tagore (1879: 512-13) has quoted a Sanskrit text which says that ‘a gem coloured like moss or onion, and freckled like the branched fibrous root of a tree, is called a gañja or mocha-stone: