Black Mother of Pearl 25mm Swirl Coin - 15-16 Inch Origin_Africa/Brazil Spinel is a hard vitreous

Spinel is a hard vitreous magnesium aluminum oxide

Herkimer Quartz

or color-enhanced

its coloring is the result of the chemical reaction that occurs when copper is introduced to water

and peridot

Black Mother of Pearl 25mm Swirl Coin - 15-16 Inch Origin_Africa/Brazil Spinel is a hard vitreousMother of Pearl, also known as Nacre, is an iridescent composite of organic and inorganic material most known for being the coating of pearls. It is produced by certain molluscs as an inner shell layer, and forms around pieces of sand or other irritations within such a molluscs shell to create pearls. Mother of Pearl is white with an iridescent sheen.