sedimentary

Jasper containing fossilized inclusions

Silicon Dioxide (SiO2) with trace impurities and biogenic inclusions

Hardness: 6.5-7 (Mohs scale), Color: Dark brown to mottled earth tones with lighter fossil centers, Luster: Vitreous to dull, Crystal structure: Microcrystalline/Cryptocrystalline, No cleavage, Specific gravity: 2.6-2.9

Hardness: 6

Identified March 29, 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 silicification of fine-grained sediment or organic matter. Over millions of years (often Mesozoic or Cenozoic), silica-rich water permeates the sediment, replacing organic structures with quartz/chalcedony. This specific piece appears to be a stream-tumbled pebble.

Uses & applications

Commonly used for lapidary work (cabochons), jewelry making, landscape stone, and as a decorative collector's item due to its unique patterns.

Geological facts

Jasper is an opaque variety of chalcedony. When it contains visible fossils like shells, coral, or crinoids, it is often nicknamed 'Fossil Jasper.' The circular white/grey inclusion in the center appears to be a small cross-section of a fossilized aquatic organism.

Field identification & locations

Identify in the field by its hardness (will scratch glass), smooth waxy texture when wet, and the presence of intricate or circular 'eyes' which are fossil cross-sections. Commonly found in riverbeds and gravel deposits worldwide.

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