sedimentary

Jasper or Chert

Silicon Dioxide (SiO2)

Hardness: 6.5 - 7 (Mohs scale); Color: green, yellow, tan; Luster: waxy to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: none; Fracture: conchoidal or sub-conchoidal.

Hardness: 6
Color: green, yellow, tan
Luster: waxy to dull

Identified April 10, 2026More sedimentary →

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Physical properties

Hardness: 6.5 - 7 (Mohs scale); Color: green, yellow, tan; Luster: waxy to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: none; Fracture: conchoidal or sub-conchoidal.

Formation & geological history

Formed through the accumulation of silica-rich microfossils (like radiolaria or diatoms) or secondary chemical precipitation in marine or volcanic environments. Often associated with the Paleozoic to Cenozoic eras.

Uses & applications

Commonly used for lapidary work including cabochons and beads, landscaping decoration, and historically for primitive tools and arrowheads.

Geological facts

Jasper is a cryptocrystalline variety of quartz. This particular specimen appears to be a river-worn or 'rough' piece with significant weathering, possibly containing impurities like chlorite or iron which provide the green and yellowish hues.

Field identification & locations

Identify in the field by its waxy texture when broken, high hardness (cannot be scratched by a steel knife), and characteristic smooth, rounded weathering in riverbeds. Common in many world locations including Oregon, Idaho, and Madagascar.