Jasper

Physical Properties

Hardness: 6.5-7 (Mohs); Color: Reddish-brown; Luster: Dull/Waxy; Crystal Structure: Microcrystalline/Trigonal (Cryptocrystalline quartz); Cleavage: None (Conchoidal fracture); Specific Gravity: 2.58–2.91.

Formation & Geological History

Formed through the infiltration of silica into fine-grained volcanic ash or clay, often associated with hydrothermal circulation. It typically dates from various eras, ranging from the Precambrian to more recent sedimentary cycles.

Uses & Applications

Used primarily in lapidary arts for jewelry, decorative ornaments, and carvings. Historically used for tools like scrapers and arrowheads due to its hardness and sharp fracture edges.

Geological Facts

Jasper is an opaque variety of chalcedony. Its red or brown color is usually caused by the inclusion of iron oxides (hematite or goethite). It has been used since antiquity as a favored gemstone in the ancient world, especially in seals and amulets.

Field Identification & Locations

Identify in the field by its opacity (it will not let light through even at thin edges, unlike agate), its smooth waxy feeling when wet, and its inability to be scratched by a steel knife. Commonly found in river beds, beaches, and desert environments worldwide.

Identified on: 4/23/2026

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