A flaw is a an imperfection in a gemstone. The delicately-detailed jewelry is used as pins, earrings, pendants, etc. This glassy, lustrous mineral is found in lava flows, and obsidian stones can be massive. Most obsidian is 70 percent silica. Obsidian has a hardness of 5 and a specific gravity of 2.35.
Crystals are transparent to translucent .
The chemical formula for fluorite is CaF 2 . Fluorite is found all around the world. Fobs were worn hanging from a pocket. Stones are rarely foiled any more. It is used to attach the two ends of a necklace or bracelet .