Gem-quality chrysoprase from Haneti-Itiso area, central Tanzania

Abstract

Gem-quality, apple-green, Ni-bearing chalcedonic quartz occurs as near-surface veins in silicified serpentinite in the Haneti-Itiso area, Central Tanzania. The mineralogical properties of the chrysoprase are described. Miscroscopically the Tanzanian chrysoprase consists of spherules which are highly disordered, concentric, and composed of bipyramidal quartz, chalcedony, quartzine, and opal-A. They were classified into four main types according to the shell arrangement. -from Authors