Dendritic Jasper

Physical Properties

Hardness: 6.5-7 (Mohs scale); Color: Brown, tan, or yellow base with black or dark green tree-like inclusions; Luster: Vitreous to waxy; Structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91.

Formation & Geological History

Formed through the infiltration of mineral-rich water (carrying manganese or iron) into the cracks and pore spaces of microcrystalline quartz or volcanic ash. Over geological time, these fluids evaporate, leaving behind dendritic (branch-like) patterns that resemble trees or moss.

Uses & Applications

Primarily used for lapidary work, jewelry (cabochons), ornamental carvings, and as a popular specimen for rock and mineral collectors.

Geological Facts

The term 'dendritic' comes from the Greek word 'dendron,' meaning tree. These patterns are not fossils of plants, but rather crystal growths called pseudofossils.

Field Identification & Locations

Identify in the field by its high hardness (not scratched by steel), smooth waxy feel when wet or polished, and the characteristic branching 'fern' patterns. Commonly found in riverbeds or volcanic regions globally, including Oregon (USA), India, and Brazil.

Identified on: 4/21/2026

Mode: Standard