sedimentary

Black Jasper

Silicon Dioxide (SiO2) with impurities

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale; Color: Deep black to charcoal gray; Luster: Dull to vitreous (waxy when polished); Crystal Structure: Microcrystalline/Cryptocrystalline; Cleavage: None; Specific Gravity: 2.58-2.91

Hardness: 6
Color: Deep black to charcoal gray
Luster: Dull to vitreous (waxy when polished)

Identified May 31, 2026More sedimentary →

Explore Black Jasper in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed through the deposition of silica-rich sediments or the hydrothermal replacement of organic material and volcanic ash. Often found in association with ancient volcanic activity or marine sedimentary environments.

Uses & applications

Primarily used as a gemstone for jewelry, cabochons, and decorative carvings. In metaphysical circles, it is used as a 'grounding' stone. Historically used for flint-knapping tools.

Geological facts

Also known as 'Basanite' when it is a fine-grained form used as a touchstone for testing the purity of gold and silver. It is an opaque variety of chalcedony.

Field identification & locations

Identify in the field by its smooth, conchoidal fracture, extreme hardness (won't scratch with a knife), and complete opacity even at thin edges. Commonly found in riverbeds or coastal areas as water-worn pebbles.