Silver Sheen Obsidian Identification Guide
Identify silver sheen obsidian by its glassy conchoidal fracture, single silvery directional sheen, and the tests that separate it from gold sheen and rainbow obsidian.
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What Silver Sheen Obsidian Looks Like
Silver sheen obsidian is natural volcanic glass that shows a bright silvery shimmer when tilted, caused by reflection off a layer of aligned microscopic gas bubbles trapped during rapid cooling. The body is black to dark gray, and the sheen appears as a silvery-white sweep across the polished surface.
- Color: black to dark gray with a silvery-white sheen
- Luster: vitreous (glassy)
- Transparency: translucent at thin edges to opaque
- Habit: massive glass with no crystal structure; polished to display the sheen
Step-by-Step Field-ID Checklist
- Tilt under one light source. A bright silvery sheet of light moves across the surface — present only at certain angles, proving it is internal.
- Check the fracture. Fresh chips break with smooth, curved, conchoidal surfaces and sharp edges, the obsidian signature.
- Hardness check. It scratches glass with effort; a steel knife barely marks it (~5–5.5).
- Inspect for cleavage. None — only conchoidal fracture (rules out feldspar look-alikes).
- Edge transparency. Thin edges often transmit light, confirming glass.
Key Diagnostic Tests
- Mohs hardness: about 5–5.5.
- Streak: white.
- Cleavage/fracture: no cleavage; conchoidal fracture.
- Specific gravity: about 2.35–2.6.
- Acid: no reaction.
- Optical clue: monochrome silvery sheen (versus golden or multicolored varieties).
Common Look-Alikes and How to Tell Them Apart
- Gold sheen obsidian: the same glass but with a golden sheen rather than silvery; tilt to see the dominant sheen color.
- Silver peacock/rainbow obsidian: these show multicolored or ringed iridescence; silver sheen shows a single silvery flash.
- Labradorite: flashes color too, but it is a crystalline feldspar with cleavage and hardness 6–6.5; obsidian has conchoidal fracture and no cleavage.
- Hematite/specular gray minerals: metallic-gray minerals are much heavier (hematite SG ~5) and give a red-brown streak; obsidian is light with a white streak.
- Black glass slag (man-made): often shows bubbles and may lack a single coherent sheen layer, and has no natural occurrence context.
The identifying package is glassy conchoidal fracture + hardness ~5–5.5 + a single silvery directional sheen + no cleavage + white streak.
Where Silver Sheen Obsidian Is Found
Sheen obsidian forms in rhyolitic lava flows that cool fast enough to remain glassy while trapping aligned bubble layers. It is mined commercially in Mexico and found in young volcanic regions of the western United States (Oregon, California, Idaho, Arizona, New Mexico), as well as in Iceland and other volcanic areas. Look for it at the glassy margins and interiors of silica-rich lava flows.
Frequently asked questions
How can you tell if it's real silver sheen obsidian?
Look for natural glass with conchoidal fracture, hardness about 5–5.5, no cleavage, a white streak, and a single silvery sheen that sweeps across the surface only at certain tilt angles under a light.
What causes silver sheen obsidian's shimmer?
The shimmer comes from light reflecting off a layer of microscopic, aligned gas bubbles trapped in the glass during rapid cooling, producing a directional silvery sheen.
Silver sheen vs gold sheen obsidian — what's the difference?
They are the same volcanic glass with the same tests; the difference is the sheen color — silvery-white in silver sheen and golden in gold sheen, determined by the bubble layer.
Silver sheen obsidian vs labradorite — how do I tell them apart?
Labradorite is a crystalline feldspar with flat cleavage planes and hardness 6–6.5, while silver sheen obsidian is glass with conchoidal fracture and no cleavage.
Silver Sheen Obsidian identified by the community
Recent Silver Sheen Obsidian specimens identified with Rock Identifier.
