Obsidian, a naturally occuring glass, has a conchoidal fracture. Photo by Siim Seep. Licensed under CC By-SA 2.5.
Translucent Black Natural Glass Rough
Obsidian, a naturally occuring glass, has a conchoidal fracture. Photo by Siim Seep. Licensed under CC By-SA 2.5.
Article: What is Gemstone Cleavage?
Credit: Siim Seep
| Gemstone | Natural Glass, Obsidian, Artisanal Glass |
| Natural or man made | Natural |
| Gem State | Rough |
| Color | Black |
| Transparency | Translucent |