sedimentary

Jasper (Iron-rich)

Silicon Dioxide (SiO2) with Fe2O3 (Hematite) impurities

Hardness: 6.5-7 (Mohs scale); Color: Brownish-tan to earthy yellow with dark rinds; Luster: Waxy to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.9

Hardness: 6
Color: Brownish-tan to earthy yellow with dark rinds
Luster: Waxy to dull

Identified March 5, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from the deposition of silica from water (hydrothermal or sedimentary) which gradually crystallizes into a microcrystalline structure. Often found in Banded Iron Formations or as nodules in sedimentary host rocks.

Uses & applications

Used primarily for lapidary work, jewelry (cabochons), and as a collector's stone. Historically used for making tools due to its conchoidal fracture which creates sharp edges.

Geological facts

Jasper is an opaque variety of chalcedony. Its patterns and colors are caused by the inclusion of minerals like iron, which provides the yellow-brown hues seen in this specimen. It has been a popular gemstone since antiquity, mentioned in various historical texts.

Field identification & locations

Identify in the field by its hardness (it will scratch glass), its opaque nature, and the smooth, curved fracture surfaces. Commonly found in riverbeds, desert pavements, and mountainous regions like the western USA, India, and North Africa.

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