Lace Obsidian Identification Guide
How to recognize lace obsidian by its swirling banded patterns within glassy volcanic obsidian.
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What Lace Obsidian Looks Like
Lace obsidian is a patterned variety of volcanic glass (obsidian) in which flow banding, gas, and trace iron oxides create intricate lacy, swirling, web-like patterns. The base is glassy black, gray, or brown, threaded with reddish-brown, orange, tan, or cream bands that twist into delicate lace-like designs. Like all obsidian it has a brilliant glassy (vitreous) luster and breaks with sharp conchoidal fracture. It is translucent on thin edges and opaque in the body.
Step-by-Step Field ID Checklist
- Confirm it's glass - bright vitreous luster, no visible crystals or grains.
- Check the fracture - smooth, curved, shell-like (conchoidal) breaks with razor edges.
- Look for the lace pattern - fine swirling bands of contrasting color, not straight stripes.
- Test hardness - about Mohs 5-5.5, will scratch glass faintly and be scratched by quartz.
- Hold to light - thin edges glow translucent brown or red.
Key Diagnostic Tests
- Conchoidal fracture: Diagnostic of natural glass; agate also shows it but is harder.
- Mohs hardness: 5-5.5 (softer than quartz/agate at 7).
- Luster: Glassy, sometimes greasy.
- Streak: White to pale gray.
- No crystals, no cleavage, no acid reaction, not magnetic.
- Lightweight for its size (SG ~2.35-2.6), warmer to the touch than glassy stones.
Common Look-Alikes and How to Tell Them Apart
- Agate (especially crazy lace agate): Harder (Mohs 7), will scratch a knife and obsidian; bands are more sharply defined and the material is chalcedony, not glass.
- Manufactured glass/slag: Often has air bubbles in regular shapes and overly uniform color; natural lace obsidian's banding is irregular and flow-related.
- Mahogany obsidian: Same glass but with broad red-brown and black patches rather than fine lace swirls.
- Flint/chert: Duller, waxier luster and harder (7).
Where Lace Obsidian Is Found
Obsidian forms where silica-rich (rhyolitic) lava cools too fast to crystallize. Lace-patterned varieties come from the volcanic regions of Mexico (a major source of patterned obsidian), the western U.S. (Oregon, Nevada, California), and other young volcanic terranes.
Frequently asked questions
How can you tell if lace obsidian is real?
Real lace obsidian is natural volcanic glass: it has a bright glassy luster, breaks with smooth conchoidal (shell-like) fracture and sharp edges, is about Mohs 5-5.5, and shows irregular flow-related lace banding rather than uniform manufactured color.
What is the difference between lace obsidian and crazy lace agate?
Lace obsidian is volcanic glass (hardness 5-5.5) while crazy lace agate is chalcedony (hardness 7). The agate will scratch the obsidian, and its bands are crisper and more banded-quartz in character.
What does lace obsidian look like?
It is glassy black, gray, or brown obsidian threaded with swirling lacy bands of reddish-brown, orange, or cream, with a high glassy shine.
Is lace obsidian man-made glass?
No. It is natural volcanic glass. Man-made glass and slag usually show regular bubbles and uniform color, whereas lace obsidian has irregular, flow-formed banding.