Green Obsidian Identification Guide
How to identify green obsidian volcanic glass, recognize its conchoidal fracture, and tell genuine material from manufactured green glass.
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What Green Obsidian Looks Like
Green obsidian is a natural volcanic glass (amorphous, non-crystalline) tinted green by trace iron and other elements. It is typically transparent to translucent with a brilliant vitreous (glassy) luster, ranging from olive and bottle-green to bright emerald tones. Important caveat: genuinely natural green obsidian is uncommon, and much material sold as "green obsidian" is actually manufactured glass or slag.
Step-by-Step Field-ID Checklist
- Inspect the fracture: look for smooth, curved conchoidal fracture with razor-sharp edges—classic of glass.
- Hold to light: natural obsidian is often translucent with cloudy flow lines or tiny crystallites; pure even color with bubbles suggests man-made glass.
- Look for gas bubbles: abundant round bubbles strongly indicate manufactured glass.
- Test hardness: scratches glass faintly; itself around Mohs 5–5.5.
- Feel the weight: light to moderate; obsidian is not dense.
Key Diagnostic Tests
- Mohs hardness: 5–5.5
- Streak: white
- Fracture: conchoidal; no cleavage (amorphous glass)
- Specific gravity: ~2.35–2.6
- No acid reaction; non-magnetic
- Under magnification, natural obsidian may show flow banding and crystallite "snowflake" or needle inclusions; factory glass shows uniform color and bubbles
Common Look-Alikes and How to Tell Them Apart
- Manufactured/slag glass: The most common confusion—look for perfectly even color, mold seams, and many spherical bubbles. Natural obsidian shows flow lines and mineral crystallites.
- Moldavite: A natural green tektite with a wrinkled, etched surface and schlieren; obsidian is volcanic and usually smoother with flow banding.
- Green glass bottles/cullet: Same conchoidal fracture but with seams and consistent tint.
- Green chalcedony/jasper: Harder (7), opaque to translucent, and not glassy-brittle in the same way.
- Fluorite: Has cleavage (octahedral) and is crystalline; obsidian has none.
Where Green Obsidian Is Found
Obsidian forms at the margins of rhyolitic lava flows. Sources include the United States (Oregon, California, Idaho), Mexico, Iceland, Italy (Lipari), and Armenia. Naturally green-tinted obsidian is rare; verify locality before assuming authenticity.
Frequently asked questions
How can you tell if it's real green obsidian?
Genuine green obsidian shows conchoidal fracture, a hardness around 5–5.5, flow banding or tiny crystallite inclusions, and lacks the abundant round gas bubbles and mold seams of manufactured glass.
Is green obsidian natural or man-made?
Naturally green obsidian exists but is uncommon; a great deal of bright green 'obsidian' on the market is manufactured glass or slag, so check for bubbles, even color, and seams.
What does green obsidian look like?
It is a glassy, translucent green stone with smooth curved fracture surfaces, sharp edges, and sometimes faint flow lines, ranging from olive to bright emerald.
Green obsidian vs moldavite: how do I tell them apart?
Moldavite is a tektite with a distinctive wrinkled, etched and pitted surface and internal swirls, while obsidian is volcanic glass that is typically smoother with flow banding.