of the best quality were found in altered talc-tremolite schists at a distance of 15 to 30 cm from enclosed segregations of sodium feldspar. The colour of emerald
is deep-green. Only 10 to 15% of all emerald
raw material extracted at this deposit is suitable for beneficiation and cutting. The crystals display a distinct dichroism from bluish green to yellow-green, which may impart a yellow tint as a result of random faceting. The density is about 2.77 g/cm³. The most common inclusions are tremolite needles, actinolite, and minor chlorite and talc.
Ref: E.Ya.Kievlenko, Geology of gems, 2003, p. 88 - 89