This article is reproduced with kind permission from the National Gem and Jewellery Authority. This ia a black amorphous mineral from Sri Lanka-D.P Gunasekera, FGA ,President: Crystals gallery-Gem Lab. Chemical analysis was performed on a JEOL 733 electron microprobe equipped with Tracor Northern 5550 and 5600 automation. Data reduction was done with a PAP routine […]