sedimentary

Black Jasper

Black Jasper (Silicate mineral - SiO2)

Hardness: 6.5-7 (Mohs scale); Color: Black with potential grey or deep blue undertones; Luster: Vitreous to waxy; Crystal structure: Microcrystalline (Trigonal); Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.91.

Hardness: 6
Color: Black with potential grey or deep blue undertones
Luster: Vitreous to waxy

Identified April 16, 2026More sedimentary →

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 accumulation of silica in sedimentary environments or through the replacement of organic materials or volcanic ash by silica-rich fluids. Often dated back to the Paleozoic or Mesozoic eras depending on the local geology.

Uses & applications

Used primarily in lapidary work for cabochons, beads, and tumbled stones. Historically used as a 'touchstone' to test the purity of gold and silver.

Geological facts

Black Jasper, also known as Basanite in certain archaeological contexts, was used by ancient metallurgists to determine the gold content of alloys by the color of the streak left on the stone's surface.

Field identification & locations

Identify by its high hardness (won't be scratched by a steel knife) and its smooth, waxy texture when polished. Found commonly in areas with high silica activity, such as riverbeds or coastal regions in India, Egypt, and the USA.

Other sedimentary specimens

See all

Sandstone or Siltstone

Arenite (if sandstone)

Sedimentary

Sandstone

Arenite (primarily SiO2)

sedimentary

Chert Breccia

Brecciated Chert (Microcrystalline Silica)

sedimentary

Sandstone Grain

Clastic Sedimentary Rock Grain (SiO2 dominated)

sedimentary

Shale or Slaty Mudstone

Argillaceous sedimentary rock

sedimentary

Sandstone

Arenite

sedimentary