Minerals and Metals in Ancient India v2.c47.181

v2.c47.181

*Turquoise* : This is a hydrous phosphate of aluminium and copper; may be considered to be an aggregate of orthophosphoric acid molecules hooked with (CuOH) and Al(OH)₂ radicals. A typical formula is H₅ (CuOH) [Al (OH)₂](PO₄)₄. Waxy luster. Colour sky blue, bluish green. Has a secondary origin through reaction of copper mineral and feldspar aluminium with apatite or organic phosphorous. Much of the turquoise used in the ancient world was odontolite or bone-turquoise formed from fossil bone. In the Harappan period, much of turquoise came from Persia, near Nishapur in Khorasan. This was found in narrow seams or in irregular patches in porphyritic trachyte, associated with limonite. A greenish blue variety comes from Siberia. Turquoise is the French word for Turkish. The mineral travelled to the West from Persia through Turkey.