Snowflake Obsidian Identification Guide

What Snowflake Obsidian Looks Like

Snowflake obsidian is black volcanic glass speckled with grayish-white, snowflake-like clusters. The black base is ordinary obsidian — amorphous, glassy, and lustrous — while the white "snowflakes" are spherulites of cristobalite, a high-temperature silica mineral that began to crystallize within the glass as it slowly devitrified. The flakes range from tiny dots to feathery rosettes scattered across the dark, glossy background. Surfaces are smooth and glassy, with sharp conchoidal fracture edges.

Step-by-Step Field ID Checklist

1. Identify the base glass. Confirm a black, glassy, lustrous body with smooth surfaces and no visible grains.
2. Spot the snowflakes. Look for gray-white, radiating, rounded clusters (cristobalite spherulites) embedded in the black glass.
3. Examine fracture. Glassy, curved conchoidal fracture with razor-sharp edges confirms volcanic glass.
4. Test hardness. It scratches glass (about 5–5.5) but is brittle.
5. Backlight thin edges. The black glass may show faint brown translucency; the snowflakes stay opaque white.
6. Feel it. Light, smooth, and warms quickly in the hand compared with denser minerals.

Key Diagnostic Tests

• Hardness: About 5–5.5; scratches window glass, scratched by quartz and steel files.
• Streak: White to gray.
• Cleavage/fracture: No cleavage; conchoidal fracture with sharp edges.
• Density: Low, around 2.35–2.6 g/cm³.
• Acid: No reaction.
• Structure: Amorphous glass host with crystalline cristobalite inclusions (the snowflakes).

Common Look-Alikes and How to Tell Them Apart

• Plain black obsidian: Same base material but without the white spherulites; the snowflakes are the distinguishing feature.
• Flower obsidian / spiderweb patterns: Other devitrification textures in obsidian; snowflake obsidian shows discrete rounded white clusters rather than connected webbing.
• Black glass slag or man-made glass: May mimic the base but lacks natural cristobalite snowflakes; look for mold seams or bubbles and an artificial context.
• Black-and-white granite/diorite: Crystalline rock with visible interlocking mineral grains and no glassy conchoidal fracture; far harder to confuse once you see grain structure.
• Dyed/painted imitations: White spots on imitations sit on the surface and rub or chip off; real snowflakes are inside the glass.

Where Snowflake Obsidian Is Found

It forms where rhyolitic obsidian has slowly devitrified, allowing cristobalite to nucleate. The most famous commercial source is Utah (the Black Rock and related areas), with additional material from other western U.S. states (Oregon, Nevada, Arizona, California, New Mexico) and volcanic regions worldwide. Hunt in and around silicic lava flows and the weathered float downslope.