Volcanic & Metamorphic
Volcanic Glass
What it is
When lava cools so fast that atoms don't have time to arrange into crystals, the result is natural glass. Obsidian is the most common volcanic glass. Variations include snowflake obsidian (with cristobalite crystals), rainbow obsidian (thin-film interference), and Apache tears (rounded nodules).
How it forms
Forms when silica-rich (rhyolitic) lava erupts and quenches rapidly — either in air, water, or against cold rock. The lack of crystal structure makes it a mineraloid, not a true mineral.
70–75% SiO₂ + various oxides (amorphous)
Specimens
5 stones
Apache Tears
Protection · Root
Rapidly cooled 'pebbles' of glass.
Black Obsidian
Protection · Root
Rapidly cooled volcanic lava.
Obsidian
Protection · Root
Rapid cooling; no crystal structure.
Rainbow Obsidian
Protection · Root
Magnetite inclusions in volcanic glass.
Snowflake Obsidian
Protection · Root
De-vitrifying white spots in glass.