Cosmic Obsidian Identification Guide
Identify cosmic obsidian by its glassy black body, swirling galaxy-like sheen patterns, conchoidal fracture, and how it differs from other sheen obsidians.
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What Cosmic Obsidian Looks Like
Cosmic obsidian is a trade name for a variety of sheen obsidian: volcanic glass whose dark body, when polished and tilted, reveals swirling, nebula- or galaxy-like patches of metallic sheen (gold, silver, blue, green, and multicolor) caused by aligned microscopic gas bubbles and mineral inclusions. The base is black to very dark, glassy and lustrous, with a smooth, mirror-like polished surface. It is amorphous (a glass), so there are no crystals or cleavage. Transparency is opaque to translucent on thin edges. The defining visual is the cosmic, drifting sheen that appears only at certain angles to the light.
Step-by-Step Field ID Checklist
- Confirm it is glass. Glassy luster, conchoidal fracture, no crystals or grains.
- Tilt for sheen. Rotate under a light: cosmic obsidian shows swirling multicolor or gold/silver sheen patches that move.
- Check the body color. Black to very dark with the sheen riding over it.
- Look at fracture surfaces. Smooth, curved (conchoidal) chips with razor-sharp edges.
- Confirm hardness (below).
- Note the polish dependence. The cosmic effect is best on polished surfaces; rough chunks may look like plain black obsidian.
Key Diagnostic Tests
- Hardness: 5–5.5 (volcanic glass); scratched by quartz and steel; will scratch glass slightly.
- Streak: White.
- Cleavage/fracture: No cleavage; classic conchoidal fracture (curved, shell-like).
- Magnetism: Generally none to very weak.
- Acid: No reaction.
- Density: Low, ~2.35–2.6 g/cm³; lighter than quartz, warmer feel than glass.
- Transparency: Thin edges often transmit a brownish or smoky light.
Common Look-Alikes and How to Tell Them Apart
- Rainbow/gold/silver sheen obsidian: Same material with a single-color or full-spectrum sheen; cosmic obsidian shows multicolor swirling galaxy-like patterns. The distinction is largely visual/trade naming.
- Plain black obsidian: No sheen; cosmic obsidian shows angle-dependent metallic sheen.
- Manufactured glass/goldstone: Goldstone (glass with copper flecks) has uniform sparkly glitter, not a soft drifting sheen; manufactured glass often has bubbles and mold seams.
- Labradorite/spectrolite: A crystalline feldspar with labradorescence, harder (6–6.5) with cleavage; obsidian is glass with conchoidal fracture and no cleavage.
- Black onyx/chalcedony: Harder (7), waxier, no conchoidal glass fracture or sheen.
Where It Is Typically Found
Obsidian forms where felsic (rhyolitic) lava cools too quickly to crystallize, at lava flows, domes, and volcanic margins. Sheen varieties marketed as cosmic obsidian come mainly from Mexico and the western United States; the material is then cut and polished to reveal the cosmic effect.
Frequently asked questions
What is cosmic obsidian?
Cosmic obsidian is a trade name for a sheen obsidian, volcanic glass with a dark body that displays swirling galaxy- or nebula-like metallic sheen in gold, silver, blue, green, and multicolor due to aligned microscopic bubbles and inclusions.
How can you tell if it's real cosmic obsidian?
Genuine obsidian is volcanic glass: glassy luster, conchoidal fracture, hardness about 5–5.5, white streak, no cleavage, and light weight. Cosmic obsidian additionally shows an angle-dependent swirling multicolor sheen on polished surfaces, not a uniform glitter like manufactured goldstone.
What is the difference between cosmic obsidian and rainbow obsidian?
Both are sheen obsidians from aligned inclusions. Rainbow obsidian typically shows concentric or layered spectral bands, while cosmic obsidian shows swirling, galaxy-like multicolor sheen patches. The names are largely descriptive of the pattern.
Is cosmic obsidian natural or man-made?
The base material is natural volcanic glass. The cosmic sheen is a natural optical effect from microscopic inclusions, revealed by cutting and polishing. Beware confusing it with man-made goldstone glass, which has uniform copper glitter.