Obsidian
Obsidian is a rock with the chemical formula SiO2. It has a Mohs hardness of 5.5 – 6 on the Mohs scale and vitreous to glassy luster.
Obsidian properties
| Type | Rock |
|---|---|
| Chemical formula | SiO2 |
| Mohs hardness | 5.5 – 6 on the Mohs scale |
| Luster | Vitreous to glassy |
| Typical colors | Black, brown, green, red, and can exhibit patterns (e.g., snowflake, rainbow) |
| Formation | Forms when molten lava cools rapidly without crystallization |
| Rarity | 4 / 10 |
Mohs hardness 5.5–6 — fairly hard
1 · Talc5 · Apatite10 · Diamond
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