Iolite 4-7mm Faceted Rondelle - 18 Inch 6X8 It is a phyllosilicate composed

It is a phyllosilicate composed of silicon

but those varieties are transparent

Glacierite has a beautiful blue color that comes from trace amounts of cobalt and vanadium

and Side Cutters

Iolite 4-7mm Faceted Rondelle - 18 Inch 6X8 It is a phyllosilicate composedIolite most commonly occurs in shades of blue to gray, violet or indigo. It displays a visual property called pleochroism, which means that it can appear to be different colors as it shifts in the light. According to Norse legend, Viking explorers used thin pieces of Iolite as the worlds first polarizing lens to help them determine the exact location of the sun for navigation.