Black Spinel 10mm Natural Round - 15-16 Inch rqtz-spe-str It forms over long periods

It forms over long periods as mineral-rich water moves through aluminous rock

white and occasionally gray or brown

White Howlite is named for Canadian mineralogist Henry How

rainbow effect of light refracting off of the air bubbles inside of the stone

Black Spinel 10mm Natural Round - 15-16 Inch rqtz-spe-str It forms over long periodsSpinel is a hard vitreous magnesium aluminum oxide, and comes in a range of other colors, but those varieties are transparent. Black Spinel not only has the dark color, but it is opaque as well, rendering its black especially deep and mysterious. Sometimes called the "Black Prince's Ruby" for its role in the English crown. It has been mistaken for ruby and sapphire at times, but can be distinguished by its structure and its lower relative hardness.