Snowflake Obsidian
Volcanic glass (SiO2-rich) with cristobalite spherulites
A black volcanic glass speckled with gray-white cristobalite snowflakes, formed as obsidian begins to crystallize.
- Mohs hardness
- 5-6
- Color
- Black with gray-white snowflake-like patches
- Type
- igneous
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Overview
Snowflake Obsidian is a variety of obsidian, a natural volcanic glass, distinguished by gray-white snowflake-like patches scattered across its black body. The snowflakes are clusters (spherulites) of the mineral cristobalite, a form of silica that begins to crystallize within the glass.
Like all obsidian it is amorphous (non-crystalline) glass formed from rapidly cooled, silica-rich lava, and it breaks with a sharp conchoidal fracture. The contrast between the black glass and the radiating white spherulites makes it a popular ornamental stone.
It takes a high polish and is widely used for tumbled stones, beads and carvings.
Formation & geology
Snowflake Obsidian forms from felsic (high-silica) lava that cools so quickly it solidifies as glass rather than crystallizing into minerals. Over time, or as the glass begins to devitrify, silica within the obsidian crystallizes into radiating spherulites of cristobalite, which appear as the white snowflake patterns.
This occurs in volcanic regions where rhyolitic lava flows and domes are found. Notable sources include the western United States (Utah, Oregon, Nevada, Arizona), Mexico, and other volcanic areas worldwide.
How to identify it
Snowflake Obsidian is glassy black with distinctive gray-white snowflake or floret patches, a vitreous luster, and conchoidal fracture producing sharp curved edges. Hardness is 5-6 (scratches glass with difficulty, scratched by quartz); streak is white. It is amorphous glass, so it shows no crystal faces or cleavage.
Look-alikes: Plain black obsidian lacks the white spherulites. Flower obsidian and merlinite differ in pattern. Dyed or glass imitations may have bubbles; natural obsidian can also contain small bubbles. The combination of glassy black body, conchoidal fracture and gray cristobalite snowflakes is diagnostic.
Uses & significance
Snowflake Obsidian is widely used for tumbled stones, cabochons, beads, spheres, pyramids and carvings, valued for its striking black-and-white contrast and high polish. Obsidian in general has been used since prehistory for sharp blades, arrowheads and tools because of its keen conchoidal edges.
It is inexpensive and prized mainly for ornamental and lapidary use. Pieces with well-defined, evenly distributed snowflakes are most attractive.
Metaphysically it is associated with balance, calm and grounding (the root chakra), though these claims are not scientifically supported.
Frequently asked questions
What are the snowflakes in snowflake obsidian?
They are spherulites, radiating clusters of the silica mineral cristobalite that crystallize within the black volcanic glass.
Is snowflake obsidian man-made?
No, it is a natural volcanic glass; the snowflake patterns form as cristobalite crystallizes inside obsidian over time.
Can snowflake obsidian go in water?
Brief contact is fine, but avoid prolonged soaking; as a glass it can be chipped and is best wiped clean and dried.
Is obsidian a rock, mineral or glass?
Obsidian is a natural volcanic glass and is classed as an igneous rock; it is amorphous, so it is not a true mineral with a crystal structure.
Snowflake Obsidian guides
In-depth guides for identifying, valuing, and understanding Snowflake Obsidian.
Snowflake Obsidian identified by the community
Real specimens identified with Rock Identifier.
