Black Jasper

Physical Properties

Hardness: 6.5-7 (Mohs scale); Color: Deep black with some white or grey veining; Luster: Vitreous to waxy when polished; Crystal structure: Microcrystalline/Cryptocrystalline; Specific Gravity: 2.6-2.9.

Formation & Geological History

Formed through the accumulation of fine silica-rich sediment or volcanic ash. The black coloration is often due to the presence of manganese oxides or organic carbon within the silica matrix.

Uses & Applications

Commonly used in jewelry, as tumbled stones for pocket charms, in ornamental carvings, and as a decorative stone in aquariums or landscaping.

Geological Facts

Black Jasper is sometimes referred to as 'Basanite' when used as a touchstone to test the purity of gold and other precious metals. It is a dense, opaque variety of chalcedony.

Field Identification & Locations

Identify in the field by its hardness (it will scratch glass), its opaque nature, and the smooth, conchoidal fracture if broken. Often found as rounded pebbles in riverbeds or coastal areas.

Identified on: 4/19/2026

Mode: Standard