Leopard Obsidian Identification Guide
Identify leopard obsidian, a spotted volcanic glass with snowflake-like clusters, versus snowflake obsidian and porphyry.
Read the full Leopard Obsidian encyclopedia entry →
What Leopard Obsidian Looks Like
Leopard obsidian is a patterned volcanic glass: a dark (black to brown or gray) glassy base spotted with lighter gray, tan, or brownish rounded clusters that resemble a leopard's coat. The spots are spherulites or cristobalite clusters, radiating crystal growths formed as the glass began to devitrify. The base retains the classic obsidian glassy (vitreous) luster and breaks with conchoidal fracture, while the spots may appear slightly duller and more crystalline. It is opaque to translucent at thin edges.
Step-by-Step Field ID Checklist
- Confirm a glassy base. The dark matrix should be glossy and smooth like bottle glass.
- Examine the spots. Look for rounded, often radiating clusters scattered through the glass, like leopard rosettes.
- Check fracture. Conchoidal, shell-like curved breaks with sharp edges in the glassy matrix.
- Look at thin edges for translucency in the base glass.
- Test hardness to confirm glass-grade.
Key Diagnostic Tests
- Hardness: Mohs ~5 to 5.5; scratches with a hard steel point about like glass.
- Streak: White to pale gray.
- Fracture: Conchoidal in the matrix; the spherulite spots may chip more granularly.
- Density: ~2.4 g/cm3, light for a glassy stone.
- Acid: No reaction to HCl.
Common Look-Alikes and How to Tell Them Apart
- Snowflake obsidian: Essentially the same phenomenon (cristobalite spherulites in obsidian) but with white, snowflake-shaped clusters; leopard obsidian has larger, browner, more rosette-like spots. They grade into each other and names are partly commercial.
- Porphyritic obsidian: Contains angular feldspar phenocrysts (crystal shapes) rather than rounded radiating spherulites.
- Mahogany obsidian: Has reddish-brown swirls/streaks from iron, not discrete rounded spots.
- Dalmatian stone: A feldspar-rich rock with black tourmaline spots; it is not glassy, has higher hardness in spots, and lacks conchoidal fracture.
- Spotted jasper/porphyry: Crystalline and harder (jasper Mohs 7), no glassy conchoidal fracture.
Where Leopard Obsidian Is Typically Found
Leopard and snowflake obsidian form where rhyolitic obsidian flows slowly devitrify, growing spherulites. Common sources include the western United States (Utah, Nevada, Oregon, California) and Mexico. Look for it in eroded obsidian flows and glass-rich rhyolite fields.
Frequently asked questions
What is the difference between leopard obsidian and snowflake obsidian?
Both are obsidian with cristobalite spherulites, but snowflake obsidian has small white snowflake-shaped clusters on black glass, while leopard obsidian has larger, browner, more rosette-like spots resembling a leopard's coat. The two grade into each other and the names are partly commercial.
How can you tell if leopard obsidian is real?
Real leopard obsidian has a glassy matrix with conchoidal fracture, hardness around 5 to 5.5, low density near 2.4, and rounded radiating spherulite spots. If it lacks the glassy fracture and is harder throughout, it is likely jasper or another spotted rock rather than obsidian.
What are the spots in leopard obsidian?
The spots are spherulites, radiating clusters of cristobalite or feldspar crystals that grew as the volcanic glass slowly began to crystallize (devitrify) after eruption.
Is leopard obsidian the same as dalmatian stone?
No. Dalmatian stone is a feldspar-rich rock with black tourmaline or mineral spots and is not glassy, while leopard obsidian is volcanic glass with conchoidal fracture and spherulite spots.