Obsidian (Snowflake)
“Volcanic glass with crystal blooms”
Snowflake obsidian is a variety of obsidian in which white or gray cristobalite crystal clusters have formed within the black volcanic glass over time through a process called devitrification. The radiating crystal patterns resemble snowflakes and create a striking black-and-white contrast.
volcanic glass (SiO₂), cristobalite (SiO₂ polymorph), feldspar microcrystals
Utah (USA), Oregon (USA), Mexico, Iceland, Italy, Japan
5-5.5
Snowflake obsidian actually represents volcanic glass that's slowly 'failing' — over thousands of years, the unstable glass gradually crystallizes, and eventually all obsidian would become a fully crystalline rock.
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What process causes the white 'snowflake' patterns to form in snowflake obsidian?
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