Jasper Geode

Physical Properties

Hardness: 6.5-7 Mohs; Color: Multi-colored (red, yellow, brown, white); Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.91

Formation & Geological History

Formed through the deposition of silica from groundwater or hydrothermal fluids within cavities in volcanic or sedimentary rocks. Over millions of years, these fluids precipitate layers of microcrystalline quartz or chalcedony, often leaving a hollow center which may contain macrocrystalline quartz.

Uses & Applications

Used primarily for lapidary work, decorative display pieces, jewelry (cabochons), and metaphysical collecting.

Geological Facts

Jasper is an opaque variety of chalcedony. When it forms with a central cavity lined with crystals, it is technically a geode. Many of the most colorful specimens come from the high deserts of the American Northwest.

Field Identification & Locations

Identify in the field by its high hardness (cannot be scratched by steel), waxy texture when broken, and lack of visible grains. Common in volcanic regions and river gravels. Look for rounded, dull-looking nodules that feel heavier than expected.

Identified on: 5/14/2026

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