sedimentary

Yellow Jasper

Silicon Dioxide (SiO2) with Goethite or Iron Hydroxide inclusions

Hardness: 6.5-7 (Mohs scale); Color: Yellow to mustard/mustard brown; Luster: Waxy to vitreous; Crystal Structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91

Hardness: 6
Color: Yellow to mustard/mustard brown
Luster: Waxy to vitreous

Identified March 30, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the infiltration of silica-rich fluids into volcanic ash or sedimentary beds. The yellow color results from ferric iron (goethite) impurities during the mineralization process. It is found in rocks of various ages, commonly ranging from Precambrian to Cenozoic.

Uses & applications

Used primarily as decorative gemstones, lapidary cabochons, and in jewelry. Historically used for making tools and weapons due to its sharp conchoidal fracture.

Geological facts

Jasper is an opaque variety of chalcedony. The name 'jasper' is derived from the Greek word 'iaspis', meaning 'spotted stone'. In ancient times, it was considered a stone of protection and endurance.

Field identification & locations

Identify in the field by its distinctive waxy appearance, extreme hardness (it will scratch glass), and shell-like (conchoidal) fracture pattern. Common locations include South Africa, India, Brazil, and the Western United States.

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