sedimentary

Black Jasper with Quartz

Silicon Dioxide (SiO2) with impurities

Hardness: 6.5-7 on Mohs scale; Color: Opaque black with yellowish-white inclusions; Luster: Vitreous to waxy (when polished); Crystal structure: Microcrystalline/Cryptocrystalline; Specific Gravity: 2.6-2.9

Hardness: 6
Color: Opaque black with yellowish-white inclusions
Luster: Vitreous to waxy (when polished)

Identified June 29, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed primarily in sedimentary environments through the deposition and compaction of silica-rich particles, often associated with hydrothermal activity or volcanic ash layers. Over millions of years, impurities like iron oxides or carbon create the black coloration.

Uses & applications

Commonly used as a lapidary material for jewelry (cabochons), tumbled stones for collectors, and in metaphysical practices as a 'grounding' stone.

Geological facts

Black jasper is often called 'Basanite' when it is used as a touchstone to test the purity of gold and silver. It has been used by jewelers for this purpose for thousands of years.

Field identification & locations

Identified in the field by its opacity (it will not let light through even at thin edges), smooth conchoidal fracture if broken, and its ability to scratch glass. Often found in riverbeds or coastal areas as water-worn pebbles.

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