Identification guide · Igneous Rocks
How to Identify Snowflake Obsidian
Snowflake Obsidian is usually black and black and white with a vitreous luster and is opaque. It has a Mohs hardness of 5.5. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. Its streak is white. It is most often confused with Rhyolite, Granite, and Larvikite; the tests below separate them.
Snowflake Obsidian identification checklist
| Color | Black, Black and white | Look at a clean, dry surface in daylight. Color zoning, banding or spots are as diagnostic as the hue. |
|---|---|---|
| Luster | Vitreous | Fresh surfaces shine like glass; a dull surface usually means weathering, so chip or wet a corner. |
| Transparency | Opaque | Hold a thin edge up to a bright light and note whether light passes through. |
| Mohs hardness | 5.5 | It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. |
| Streak | White | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | None | |
| Fracture | Conchoidal | Broken surfaces show smooth, curved, shell-like scoops. |
| Specific gravity | 2.4 | Ordinary rock-like heft (specific gravity about 2.4), similar to quartz. |
Extra tests for Snowflake Obsidian
Glass check. Snowflake Obsidian shares a glassy luster and conchoidal fracture with man-made glass. Glass sits near Mohs 5.5 and often contains round gas bubbles, so a hardness test and a hand lens separate them.
Snowflake Obsidian look-alikes and how to tell them apart
Both sit near Mohs 5.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Snowflake Obsidian vs Rhyolite →
Granite is harder (Mohs 6.5) than Snowflake Obsidian (Mohs 5.5), so Granite will scratch Snowflake Obsidian and not the other way round. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. Snowflake Obsidian vs Granite →
Both sit near Mohs 5.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Snowflake Obsidian vs Larvikite →
Diorite is harder (Mohs 6–7) than Snowflake Obsidian (Mohs 5.5), so Diorite will scratch Snowflake Obsidian and not the other way round. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will.
Field tips
- Look for glossy black glass with gray-white snowflake-like patches and a conchoidal fracture.
- Snowflake obsidian is glassy with no crystal faces and no cleavage.
- The pale spherulites are embedded in the glass rather than sitting on the surface.
Snowflake Obsidian identification FAQ
How can you tell if a rock is Snowflake Obsidian?
Check the color (black and black and white), the vitreous luster, a Mohs hardness of 5.5 and a white streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Snowflake Obsidian?
Snowflake Obsidian has a Mohs hardness of 5.5. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will.
What is the difference between Snowflake Obsidian and Rhyolite?
Snowflake Obsidian (Mohs 5.5, vitreous luster) and Rhyolite (Mohs 5.5–7, dull to vitreous (glassy groundmass) luster) look alike, but hardness, streak and heft usually separate them. See the full Snowflake Obsidian vs Rhyolite comparison for a side-by-side table.
Is Snowflake Obsidian worth anything?
Entry-level Snowflake Obsidian specimens sell for around $3, typical collector pieces about $25, and premium examples $120 or more depending on size, quality and locality.
What color is Snowflake Obsidian?
Snowflake Obsidian is most often black and black and white. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
