Snowflake Obsidian (or similar porphyritic volcanic rock)

Hardness: 6-7 (Mohs scale), Color: Primarily dark gray to black with white or lighter gray phenocrysts, Luster: Vitreous to dull, Crystal structure: Porphyritic (large crystals within a finer-grained matrix), Cleavage: None (in the groundmass), Specific gravity: 2.7-3.0

Formed from the rapid cooling of viscous lava, typically rhyolitic or dacitic in composition. The formation of the 'snowflakes' (spherulites) occurs during cooling as a result of devitrification (crystallization of glassy material). Geological age varies depending on the volcanic activity that produced it, ranging from relatively recent to millions of years old.

Predominantly used for ornamental purposes, including jewelry (cabochons, beads), carvings, and decorative objects. It's popular in lapidary work due to its attractive contrasting patterns.

Also known as 'Flower Obsidian' or 'Snowflake Obsidian in Basalt/Andesite' due to its appearance. It is a volcanic rock. The white 'snowflake' patterns are radial clusters of spherulites, typically composed of cristobalite and feldspar, which grow within the darker glassy matrix of the obsidian during cooling. While commonly referred to as snowflake obsidian, if it is not purely volcanic glass, it is more accurately described by the rock type containing these formations.

Identify in the field by its dark (usually black) color with distinctive white to gray radial patterns resembling snowflakes. It has a conchoidal fracture (smooth, curved breaks) if it's true obsidian, or a more irregular fracture if the groundmass is crystalline. Commonly found in areas with past volcanic activity, such as the Western United States (e.g., Oregon, Utah), Mexico, and other volcanically active regions worldwide. Tips for collectors: Look for areas with obsidian flows or deposits. The presence of spherulites makes it less brittle than pure obsidian, making it more durable for handling.