Ice Obsidian 13x18mm Rectangle - 8-Inch 10x12-12x16 Amethyst is a beautiful stone

Amethyst is a beautiful stone (normally purple)

Mica is heat-resistant and does not conduct electricity

These inclusions are chromite

These gauges are often used to display dimensional information in science & engineering but is convenient for creative use as well

Ice Obsidian 13x18mm Rectangle - 8-Inch 10x12-12x16 Amethyst is a beautiful stoneIce Obsidian is a light brown to green to gray volcanic stone. Obsidian is formed when felsic lava cools without crystal growth. It is sometimes used for scalpel blades in cardiac surgery, as Obsidian can be formed into a blade many times sharper than steel surgical blades.