sedimentary

Yellow Jasper (Iron-stained Chert)

Silicon Dioxide (SiO2) with iron oxide (Limonite/Goethite) inclusions

Hardness: 6.5–7 on Mohs scale. Color: Mustard yellow to ochre. Luster: Dull to waxy. Crystal Structure: Microcrystalline/cryptocrystalline (Trigonal). Cleavage: None (conchoidal fracture). Specific Gravity: 2.6–2.7.

Hardness: 6
Color: Mustard yellow to ochre
Luster: Dull to waxy

Identified March 4, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from the precipitation of silica from water or hydrothermal fluids, often replacing organic material or filling pockets in volcanic rocks. The yellow color results from iron inclusions. Specimens can range from recent deposits to hundreds of millions of years old.

Uses & applications

Used primarily for lapidary work, jewelry (cabochons), carvings, and as a decorative landscape stone. Historically used for making sharp-edged tools due to its conchoidal fracturing.

Geological facts

Jasper is an opaque variety of chalcedony. It has been used since antiquity as a gemstone; the name is derived from the Greek 'iaspis', meaning spotted stone. It is often found associated with agate.

Field identification & locations

Identify in the field by its opacity (it does not transmit light even on thin edges), its hardness (it will scratch glass), and its smooth, shell-like fracture pattern. Common in riverbeds and arid regions globally.

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