Minerals and Metals in Ancient India v2.c47.2

v2.c47.2

*Actinolite* : Means ray in Greek. Calcium-magnesium-iron amphibole Ca₂ (Mg, Fe)₅ (OH)₂ (Si₄O₁₁)₂. Ca-Mg amphibole is tremolite (white). Due to iron, actinolite is dark-green. Mixture of the two is asbestos (does not contain hardening aluminium). Aluminium makes the structure hard and results in jade family of numerals (hardness 6-7). *Nephrite* may be white jade or green due to iron and manganese. The apple-green and emerald green colour of *jadeite* is due to the presence of chromium. It could be mauve or light blue also. The black colour of *chloromelanite* is due to excess concentration of iron in the structure. *Smaragdite* is near actinolite in composition but contains some aluminium. It is thin-foliated and has a light grass-green colour. The word for green is *smaragdus* in Latin and *smaragdos* in Greek.