Minerals and Metals in Ancient India v1.c11.s4.6

v1.c11.s4.6

Agate is the most important variety of chalcedony. Bauer defines agate-jasper as stones which are intermediate in character between jasper and chalcedony, and which usually show opaque, dark-coloured portions intermixed in various ways with translucent lighter coloured portions. Moss-agates are characterized by the presence of green enclosures which usually take the form of long hairs and fibres much intertwined and have the general appearance of a piece of moss. The chalcedony bead is white or very pale shade of grey, yellow brown, blue or green and uniformly coloured. Heliotrope beads differ from plasma only in that its green colour is spotted, patched or streaked with a fine blood-red. Another type of bead named 'plasma' applied to green chalcedony, the colour of which ranges from dark leek-green, the commonest shade, through pale apple green, to almost white. By far, the greatest number of beads referred to are the impure variety of massive quartz known as jasper. This is distinguished from hornstone by its large, even conchoidal fracture, the dull lustre of its fractured surface and by its perfect opacity and deep colour. The following six types of jasper: common jasper, blue jasper, red jasper, green jasper, yellow jasper and riband jasper have been distinguished in the various items found at Mohenjo-Daro. Only one bead was identified as Amazon stone. The bead in question was microcline and light green in colour. (MS-I, 544-45) Only one bead has been determined as being tachylyte or a basaltic or ultra-basic glass. In the case of silver beads, most of the silver has been converted to silver chloride by weathering, and not only are the beads covered inside and out with a thick, pimply coating of this mineral, but the metallic portion itself is impregnated with chloride to such an extent that it has become very brittle. Two greyish beads have been identified as nepheline sodalite rock, probably obtained from Kishangarh, Rajasthan. (MS-II, 546-47)