Snowflake Obsidian
Snowflake obsidian is a form of black obsidian that contains small white crystal impurities made of crystobalite. The end result is a beautiful black color with distinctive grayish white patterns throughout the surface.
Obsidian is a natural glass which is formed through volcanic activity by the cooling of molten lava. Snowflake obsidian forms when the mineral cristobalite is present and gets trapped in the obsidian as it cools. Cristobalite is a silica, similar to quartz but with a different crystal structure. As obsidian is a glass and cristobalite is a crystal, snowflake obsidian is essentially a lot of tiny crystals trapped in black glass rock.