sedimentary

Jasper and Mixed River Pebbles

Microcrystalline Quartz (Chalcedony / Jasper)

Hardness: 6.5 to 7 on the Mohs scale. Colors vary widely including yellow, brown, red, and dark gray due to various mineral impurities. Luster is typically waxy to dull. Crystal structure is microcrystalline (trigonal). Cleavage is absent (fractures conchoidally). Specific gravity ranges from 2.58 to 2.91.

Hardness: 6

Identified August 1, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the deposition and lithification of silica-rich sediments or the alteration of existing rocks by silica-rich hydrothermal fluids over millions of years.

Uses & applications

Used primarily in lapidary arts, ornamental carvings, polished stones, and as decorative gravel or landscaping stones.

Geological facts

Jasper has been used since ancient times for amulets, seals, and jewelry. The variety of colors comes from iron oxides and other mineral inclusions trapped during formation.

Field identification & locations

Commonly found in river beds, beaches, and glacial till where durable stones have been weathered and rounded by water transport over long distances.

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Sandstone or Siltstone

Arenite (if sandstone)

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Quartz pebble

Silicon dioxide (SiO2)

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Generic Pebble / Rock Fragment

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Sedimentary Sandstone

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Fossiliferous Concretion

Septarian Concretion containing Brachiopods/Crinoids

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Banded Siltstone / Mudstone Pebble

Siltstone / Argillite

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