RocksdayObsidian vs Tektite
How to tell them apart
Natural volcanic glass, formed when silica-rich lava cools so fast that crystals have no time to grow.
Photo: Ji-Elle It feels nice and warm It feels like a love storm, CC BY-SA 3.0
Natural glass blobs thrown out by meteorite impacts, often in aerodynamic shapes like buttons and teardrops.
Photo: Brocken Inaglory, CC BY-SA 3.0
Quick tests
- Texture: Obsidian is a rock — a mix of grains or minerals; Tektite is a single mineraloid.
Key differences
- Obsidian has smooth fractures and is found near volcanoes.
Side by side
| Property | Obsidian | Tektite |
|---|---|---|
| Type | Igneous rock | Mineraloid |
| Mohs hardness | 5–5.5 | 5.5–6.5 |
| Luster | Glassy | Vitreous to dull |
| Colors | Black, Brown, Red | Black, Brown |
| Crystal system / structure | Glassy | Amorphous (impact glass) |
| Specific gravity | 2.35–2.6 | 2.3–2.5 |
| Found in | Glass Buttes, Oregon; Yellowstone, Wyoming | Southeast Asia; Australia |
Properties that are the same for both are grayed out.
How to identify obsidian
- Shiny, glass-like and usually black.
- Curved, shell-shaped (conchoidal) fractures with razor-sharp edges.
- Thin edges are translucent brown or gray.
- May show white 'snowflakes' or a gold/rainbow sheen.
Structure: Glassy
Full Obsidian guide →How to identify tektite
- Black, pitted, often teardrop, disc or dumbbell shaped.
- Thin edges are dark brown, not clear.
- Lighter than they look.
Structure: Amorphous (impact glass)
Full Tektite guide →More comparisons
Could you tell them apart from a blurry close-up?
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