sedimentary

Tumbled Black Jasper

Silicon Dioxide (SiO2) with iron and carbon inclusions

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale; Color: Deep black to charcoal grey; Luster: Vitreous to waxy (when polished); Crystal structure: Microcrystalline/Cryptocrystalline; Cleavage: None; Specific Gravity: 2.58-2.91.

Hardness: 6
Color: Deep black to charcoal grey
Luster: Vitreous to waxy (when polished)

Identified June 10, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed via the deposition of silica from water into cavities or cracks within other rocks, often associated with volcanic ash or sedimentary beds. The black color is typically derived from organic matter or iron-rich impurities.

Uses & applications

Primarily used for decorative purposes, jewelry (beads, cabochons), metaphysical practices, and as a component in lapidary art.

Geological facts

Black jasper is sometimes referred to as 'Basanite' and has historically been used as a touchstone to test the purity of gold and silver ores by observing the color of the streak left behind.

Field identification & locations

Identified in the field by its opaque nature, conchoidal fracture, and extreme hardness. It won't be scratched by a steel pocket knife. Found globally, notably in the USA, India, Russia, and Madagascar.