igneous and metamorphic
Snowflake Obsidian and Green Aventurine
Volcanic Glass (SiO2 with Cristobalite inclusions) and Quartz (SiO2 with Fuchsite)
Obsidian: Hardness 5-5.5, black with white radial inclusions; Aventurine: Hardness 7, translucent green with aventurescence (sparkly luster), trigonal crystal system.
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Physical properties
Obsidian: Hardness 5-5.5, black with white radial inclusions; Aventurine: Hardness 7, translucent green with aventurescence (sparkly luster), trigonal crystal system.
Formation & geological history
Snowflake Obsidian forms during rapid cooling of silica-rich lava where mineral cristobalite forms small white 'snowflakes'. Green Aventurine is a form of quartzite containing mica, often formed through metamorphism.
Uses & applications
Commonly used for decorative ornaments, jewelry, tumbled stones for collectors, and in metaphysical practices.
Geological facts
The 'snowflakes' in the obsidian are actually internal crystals of the mineral cristobalite. The 'sparkle' in the aventurine is caused by tiny mica inclusions like fuchsite.
Field identification & locations
Both are identified by their distinct inclusions: white bursts in black glass for obsidian, and a shimmering green color for aventurine. Both are common in gift shops and mineral shows.
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