Green Sheen Obsidian Identification Guide
A guide to identifying green sheen obsidian by its reflective metallic glow, glassy fracture, and how to separate it from gold sheen and dyed glass.
Read the full Green Sheen Obsidian encyclopedia entry →
What Green Sheen Obsidian Looks Like
Green sheen obsidian is a natural volcanic glass that appears black or very dark until tilted to the light, when a green metallic sheen (schiller) sweeps across the surface. The sheen is caused by light reflecting off aligned microscopic gas bubbles or mineral crystallites (such as feldspar or magnetite) frozen in the glass. The body is opaque to translucent on edges with a brilliant vitreous luster.
Step-by-Step Field-ID Checklist
- Tilt under a single light source: the diagnostic green sheen appears and sweeps as you rotate the piece.
- Note the base color: dark gray to black without the sheen.
- Inspect fracture: smooth conchoidal fracture with sharp edges—typical glass behavior.
- Test hardness: scratches glass; itself ~5–5.5.
- Look for flow banding under magnification, indicating natural volcanic origin.
Key Diagnostic Tests
- Mohs hardness: 5–5.5
- Streak: white to gray
- Fracture: conchoidal; no cleavage (amorphous)
- Specific gravity: ~2.35–2.6
- The sheen is directional—it appears only at certain viewing angles, unlike a surface coating
- No acid reaction; non-magnetic (though included magnetite may give faint response)
Common Look-Alikes and How to Tell Them Apart
- Gold sheen obsidian: Same mechanism but golden reflection; some pieces show both. Distinguished simply by sheen color.
- Rainbow obsidian: Shows multiple banded colors rather than a single green sweep.
- Silver sheen obsidian: White/gray sheen from bubble layers.
- Dyed or coated glass: A surface coating reflects color at all angles or flakes; true sheen is internal and angle-dependent.
- Labradorite: Crystalline feldspar with cleavage and patchy iridescence, not a single glassy sweep; obsidian has no cleavage.
- Aventurine glass (goldstone): Sparkly copper flecks rather than a smooth directional sheen.
Where Green Sheen Obsidian Is Found
Sheen obsidian comes chiefly from Mexico (notably Jalisco), with other obsidian deposits in the United States, and elsewhere along rhyolitic volcanic flows. The sheen variety depends on consistent bubble/crystallite alignment within the flow.
Frequently asked questions
How can you tell if it's real green sheen obsidian?
Real green sheen obsidian looks dark until tilted, then shows a directional green metallic sheen that moves with the viewing angle, has conchoidal fracture, hardness 5–5.5, and no cleavage.
What causes the green sheen in obsidian?
The sheen comes from light reflecting off layers of aligned microscopic gas bubbles or tiny mineral crystallites trapped within the volcanic glass, creating an angle-dependent glow.
What does green sheen obsidian look like?
It appears black or dark gray, glassy and smooth, until you tilt it toward the light and a sweeping green metallic sheen appears across the surface.
Green sheen vs gold sheen obsidian: how do I tell them apart?
They form the same way; the only difference is sheen color, green versus golden, and some specimens display both depending on the orientation of the bubble layers.
Green Sheen Obsidian identified by the community
Recent Green Sheen Obsidian specimens identified with Rock Identifier.
