sedimentary

Jasper with Manganese Dendrites

Silicon Dioxide (SiO2) with Oxide Mineral Inclusions

Hardness: 6.5-7 (Mohs); Color: tan, yellow, and brownish background with black/dark grey dendritic patterns; Luster: dull to vitreous; Crystal Structure: Microcrystalline (Trigonal); Cleavage: none (conchoidal fracture); Specific Gravity: 2.58-2.91.

Hardness: 6
Luster: dull to vitreous

Identified March 25, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation of fine-grained silica-rich sediments or volcanic ash. The dark 'tree-like' patterns are manganese oxides that crystallized from mineral-rich water seeping into tiny cracks or fractures in the stone over millions of years.

Uses & applications

Commonly used as lapidary material for cabochons, beads, and decorative carvings. Larger specimens are valued by rockhounds and mineral collectors as display pieces.

Geological facts

The black patterns are often mistaken for fossilized plants (ferns or moss), but they are actually inorganic crystal growths known as dendrites. The name 'Jasper' is derived from the Greek word 'iaspis', meaning spotted stone.

Field identification & locations

Identify in the field by its hardness (it will scratch glass), its opaque nature, and the distinct branching dark patterns. Found globally, especially in desert regions or areas with high volcanic activity like the Western United States, India, and Australia.

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