Snowflake obsidian is a naturally occurring volcanic glass. It is defined by its dark, typically black, matrix speckled with white or gray inclusions that resemble snowflakes. This unique patterning makes it a sought-after material for decorative purposes, appealing to mineral collectors and artisans who specialize in jewelry making. The appearance of these light spots against the dark background gives the material its common name.
How Snowflake Obsidian Forms
Snowflake obsidian forms through a specific two-stage geological cooling process in areas with felsic volcanism. The initial step requires the rapid cooling of silica-rich lava, which prevents the formation of a crystalline structure and creates the amorphous volcanic glass known as obsidian. This fast quenching typically happens when lava flows encounter cold air or water.
For the characteristic “snowflakes” to appear, the volcanic glass must then linger at a slightly elevated temperature, roughly between 700 and 900 degrees Celsius. This secondary, slower cooling phase allows for partial devitrification. Small, radially structured clusters of the mineral cristobalite begin to crystallize within the glassy matrix. These white or gray clusters, known as spherulites, are the inclusions that create the signature snowflake pattern.
Key Global Sources
The locations where snowflake obsidian is found are tied to young, silica-rich volcanic provinces around the globe. The Western United States is a commercially significant source, with numerous deposits found across states like Oregon, Utah, and California. Oregon’s Glass Buttes and the Big Obsidian Flow in the caldera of Newberry Volcano are noted areas for high-quality specimens.
Utah and Nevada also contribute to the supply, often yielding material collected by enthusiasts and small-scale miners. Mexico is another major global contributor, with volcanic regions containing substantial obsidian deposits, some of which exhibit the characteristic snowflake pattern.
Beyond North America, snowflake obsidian is sourced from various other volcanic countries.
- Argentina, located in the geologically active Andes mountain range.
- Volcanic islands and regions across the Mediterranean, such as Italy and Iceland.
- Japan.
- Turkey.
- Scotland.
From Mine to Market
Due to its formation in surface flows, the material is frequently gathered through surface collection or shallow mining operations rather than deep excavation. The exposed volcanic glass, often found in large nodules or flow chunks, is relatively easy to access in these volcanic fields.
Once collected, the raw material must be cut and polished to fully reveal the attractive patterns hidden within the dark glass. The hardness of obsidian, rated between 5 and 5.5 on the Mohs scale, makes it suitable for shaping without being overly brittle. Its primary use is in lapidary arts, where it is fashioned into cabochons, beads, and carvings for jewelry pieces. The contrast between the dark glass and the white cristobalite spherulites is maximized through this final polishing.