sedimentary

Jasper

Jasper (Silicate mineral, SiO2)

Hardness: 6.5–7 (Mohs scale); Color: Red/orange due to iron inclusions; Luster: Dull to vitreous; Crystal structure: Trigonal (microcrystalline); Cleavage: None; Specific gravity: 2.58–2.91.

Hardness: 6
Color: Red/orange due to iron inclusions
Luster: Dull to vitreous

Identified April 3, 2026More sedimentary →

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Physical properties

Hardness: 6.5–7 (Mohs scale); Color: Red/orange due to iron inclusions; Luster: Dull to vitreous; Crystal structure: Trigonal (microcrystalline); Cleavage: None; Specific gravity: 2.58–2.91.

Formation & geological history

Formed from the deposition of silica from water (hydrothermal) or in volcanic environments, often where volcanic ash or fine sediment is saturated with silica. It can date back to any geological era from the Precambrian onwards.

Uses & applications

Used primarily as a gemstone for jewelry (cabochons), lapidary work, decorative carvings, and as a collector's stone. Historically used for making tools due to its conchoidal fracture.

Geological facts

Jasper is an opaque variety of chalcedony. The name comes from the Old French 'jaspre', meaning 'spotted or speckled stone'. It was mentioned in ancient biblical and Greek literature as a valuable stone for seals and ornamentation.

Field identification & locations

Identify in the field by its opacity (it does not transmit light even on thin edges), its hardness (can scratch glass), and its smooth, shell-like conchoidal fracture. Often found in riverbeds or near volcanic outcrops.