Obsidian
Real mineral · common · SiO₂ (amorphous)
Volcanic glass formed when silica-rich lava cools too rapidly for crystals to grow. Fractures with a conchoidal edge sharp enough to cut tissue. Used for blades and tools for thousands of years.
Identity
- Formula
- SiO₂ (amorphous)
- Chemical class
- silicate
- Also known as
- Volcanic glass, Dragon glass (folklore)
Crystallography
- Crystal system
- amorphous
- Habits
- massive, nodular
- Fracture
- conchoidal
Physical properties
- Mohs hardness
- 5.5
- Density
- 2.35 g/cm³
- Luster
- vitreous
- Colors
- black, brownish-black, dark green, red, multicolored
- Streak
- white
- Transparency
- opaque, translucent
Geology
- Origins
- volcanic
- Host rocks
- rhyolite, basalt
- Associated minerals
- pumice, feldspar
- Geography
- Iceland, Mexico, USA (Oregon, Wyoming), Japan, Turkey
Classification
- Rarity
- common
- Gem quality
- No
Arcane properties
- Affinity
- shadow, death
- Effects
- warding, necromancy
- Planar origin
- Material Plane
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