sedimentary

Jasper (specifically Red Jasper/Chert)

Silicon Dioxide (SiO2) with iron oxide inclusions

Hardness: 6.5-7 (Mohs scale); Color: Reddish-brown, earthy tones; Luster: Dull to waxy; Crystal Structure: Trigonal/Microcrystalline (cryptocrystalline quartz); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91

Hardness: 6
Color: Reddish-brown, earthy tones
Luster: Dull to waxy

Identified March 17, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the deposition of silica from water-rich environments, often near volcanic activity or in sedimentary basins. The red color is caused by iron (hematite) impurities during the mineralization process over millions of years.

Uses & applications

Used primarily as decorative stone, gemstones for jewelry (cabochons), and lapidary art. Historically used for making tools due to its sharp conchoidal fracture.

Geological facts

Jasper has been used by humans for thousands of years; it was a favorite gem in the ancient world, mentioned in various religious texts and found in Minoan carvings dating back to 1800 BC.

Field identification & locations

Identify by its hardness (cannot be scratched by a steel knife) and its smooth, shell-like (conchoidal) fracture surface. Common in the Western United States, Brazil, and India. Look for opaque stones with a waxy feel that occur as nodules or in seams.

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Sandstone or Siltstone

Arenite (if sandstone)

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Sandstone

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Shale or Slaty Mudstone

Argillaceous sedimentary rock

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Chert Breccia

Brecciated Chert (Microcrystalline Silica)

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Sandstone (Quartz-rich)

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Sandstone (with man-made markings)

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