Peanut Obsidian

Peanut Obsidian is a spherulitic variety of obsidian, natural volcanic glass dotted with grey-to-white oval clusters that resemble peanuts or small flowers. These spots are spherulites: radiating sprays of microscopic crystals (typically cristobalite and feldspar) that grew within the glass as it began to devitrify.

It is closely related to snowflake obsidian; the difference is mainly in the size and elongated, peanut-like shape of the spherulites. The black glassy matrix remains amorphous around the crystalline spots.

Each piece shows a unique scatter of pale ovals against the glossy black, making it a popular cutting and collecting material.

Peanut Obsidian begins as silica-rich lava that quenches into glass at a volcano's surface. Over time, or while still hot, the metastable glass slowly devitrifies: atoms reorganize into tiny crystals that nucleate at points and grow outward in radiating spheres called spherulites.

When these spherulites grow elongated or merge into oval clusters, they create the peanut-shaped white spots. The surrounding glass stays amorphous, preserving the contrast.

Like snowflake obsidian, it is found in older obsidian flows where partial devitrification has had time to occur, including localities in the western United States and Mexico.

Look for a black, glassy stone scattered with grey-white oval or peanut-shaped patches that have a faint radiating texture inside. Hardness is 5-5.5, luster vitreous, fracture conchoidal with sharp edges, and streak white.

The spots are slightly different in texture from the glass and may stand out subtly on a weathered surface. A thin edge of the black glass transmits brown light.

Distinguish it from snowflake obsidian (rounder, snowflake-shaped spots) and from porphyritic rocks like rhyolite (fully crystalline, harder, granular rather than glassy). If the base is glassy and softer than steel with radiating pale ovals, it is peanut/spherulitic obsidian.

Peanut Obsidian is cut into cabochons, beads, spheres, and small carvings that display the polka-dot pattern. It polishes to a high gloss; like all obsidian it can chip, so it suits pendants and decorative items more than hard-worn rings.

Obsidian generally has a long archaeological history as blades and arrowheads owing to its sharp fracture.

Metaphysically, spotted obsidians like this are regarded as grounding and balancing stones; such uses are traditional beliefs rather than established science.