Fireworks Obsidian

Fireworks Obsidian is a spherulitic variety of obsidian, natural volcanic glass containing star-like bursts of radiating crystals that resemble fireworks against the black glass. Each 'burst' is a spherulite: a spray of microscopic feldspar and cristobalite needles that grew outward from a central nucleation point as the glass partly devitrified.

It is a close relative of snowflake obsidian; fireworks obsidian's spherulites are larger and more obviously radiating, giving the explosive starburst appearance.

The surrounding matrix stays amorphous glass, so the stone keeps obsidian's conchoidal fracture and high polish while displaying striking crystalline patterns.

Fireworks Obsidian forms when silica-rich lava quenches into glass at a volcano's surface. The glass is metastable, and over time (or while still hot) it begins to devitrify: atoms reorganize into crystals that nucleate at points and grow radially outward, forming spherulites.

Where these spherulites grow large with prominent needle-like rays, they create the firework or starburst pattern. Slower, partial devitrification favors bigger, more defined bursts than the small flakes seen in typical snowflake obsidian.

Such material comes from older obsidian flows that have had time to partially crystallize, including localities in the western United States and Mexico.

Look for a black, glassy stone with grey-to-white radiating star bursts, each showing fine needles spreading from a center. Hardness is 5-5.5, luster vitreous, fracture conchoidal with sharp edges, streak white.

The bursts have a slightly different, fibrous texture from the glossy black glass and may be felt or seen on weathered surfaces.

Distinguish it from snowflake obsidian (smaller, rounder flake-like spots), from porphyritic rhyolite (fully crystalline and granular, harder), and from chrysanthemum stone (a sedimentary/metamorphic stone with mineral sprays in a different matrix). The glassy base and radiating spherulites confirm fireworks obsidian.

Fireworks Obsidian is cut into cabochons, spheres, palm stones, and carvings that show off the radiating bursts. It polishes to a high gloss; being glass it can chip, so it suits pendants and display pieces.

Obsidian in general has a long archaeological history as razor-sharp tools and arrowheads.

Metaphysically, spherulitic obsidians are regarded as grounding stones of balance and transformation, the bursts said to symbolize new beginnings; these are traditional beliefs, not scientific facts. The stone's chief appeal is its dramatic natural pattern.