sedimentary

Jasper (Iron-rich)

Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3) impurities

Hardness: 6.5-7 (Mohs scale); Color: Dark brown to black with reddish-orange iron staining; Luster: Dull to waxy; Crystal Structure: Microcrystalline (trigonal); Cleavage: None/Conchoidal fracture; Specific gravity: 2.58-2.91.

Hardness: 6
Color: Dark brown to black with reddish-orange iron staining
Luster: Dull to waxy

Identified April 1, 2026More sedimentary →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed through the infiltration of silica-rich fluids into sedimentary layers or volcanic ash deposits. Iron oxides leach into the silica during formation or through subsequent weathering, creating the dark brown/black base and orange surface streaks.

Uses & applications

Commonly used for lapidary work, cabochons for jewelry, decorative stones, and as an ornamental landscaping rock.

Geological facts

Jasper is an opaque variety of chalcedony. The name 'Jasper' is derived from the Greek 'iaspis', meaning spotted stone. It has been used since ancient times for amulets and seals.

Field identification & locations

Identify in the field by its high hardness (it will scratch glass), its heavy/dense feel, and its smooth, water-worn texture if found in riverbeds. Look for the characteristic iron-oxide 'rusting' on the surface of dark silicified stones.

Other sedimentary specimens

See all

Sandstone or Siltstone

Arenite (if sandstone)

Sedimentary

Sandstone

Arenite (primarily SiO2)

sedimentary

Shale or Slaty Mudstone

Argillaceous sedimentary rock

sedimentary

Chert Breccia

Brecciated Chert (Microcrystalline Silica)

sedimentary

Sandstone (Quartz-rich)

Arenite (SiO2)

sedimentary

Sandstone (with man-made markings)

Arenite (composed primarily of Quartz, SiO2)

sedimentary