Jasper with Chalcedony

Physical Properties

Hardness: 6.5-7 (Mohs scale); Color: Red (iron oxide) and Gray (chalcedony/quartz); Luster: Waxy to dull; Crystal structure: Microcrystalline/Trigonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.9

Formation & Geological History

Formed through the circulation of silica-rich fluids in volcanic cavities or sedimentary layers. The red color is typically caused by iron inclusions (hematite). This specimen appears to be a stream-tumbled pebble.

Uses & Applications

Used primarily for lapidary work, jewelry (cabochons), pocket stones, and decorative landscaping.

Geological Facts

Jasper is an opaque variety of chalcedony. When it shows translucent gray areas like this specimen, it demonstrates how closely related the different forms of microcrystalline quartz are. It has been used for centuries to carve seals and amulets.

Field Identification & Locations

Identify in the field by its hardness (will scratch glass), smooth waxy texture when polished, and lack of cleavage. Common in river beds and glacial till throughout North America.

Identified on: 4/30/2026

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