sedimentary

Jasper (Iron-stained Chert)

Silicon Dioxide (SiO2) with impurities of Iron Oxide

Hardness: 6.5–7 on Mohs scale. Color: Opaque reddish-brown to earthy orange. Luster: Dull to waxy. Crystal Structure: Microcrystalline (trigonal). Cleavage: None (conchoidal fracture). Specific Gravity: 2.58–2.91.

Hardness: 6
Color: Opaque reddish-brown to earthy orange
Luster: Dull to waxy

Identified March 17, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from the deposition of silica from volcanic ash or hydrothermal fluids in sedimentary environments. Its reddish hue comes from the oxidation of iron (hematite) during or after the lithification process. It can date from the Precambrian to more recent geological eras.

Uses & applications

Commonly used as a gemstone for cabochons and beads, as an ornamental stone in vases and seals, and often sought after by lapidary hobbyists for tumbling.

Geological facts

Jasper was a favorite gem in antiquity; it is mentioned in several ancient texts and was used in the high priest's breastplate in biblical times. It is unique because it is technically an impure variety of silica.

Field identification & locations

Identify in the field by its hardness (it will scratch glass), opaque nature (it does not let light through even at the edges), and smooth, shell-like fracture pattern. It is commonly found in riverbeds, deserts, and areas with volcanic activity or ancient seabed deposits.

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