sedimentary

Green Jasper (Chert)

Silicon Dioxide (SiO2)

Hardness: 6.5 - 7 on Mohs scale; Color: Dull green with iron-oxide inclusions; Luster: Vitreous to waxy; Crystal structure: Microcrystalline/Cryptocrystalline (trigonal); Cleavage: None (conchoidal fracture); Specific gravity: 2.6 - 2.9.

Hardness: 6
Color: Dull green with iron-oxide inclusions
Luster: Vitreous to waxy

Identified March 12, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation of silica-rich fluids in volcanic ash or sedimentary beds. The green color is typically caused by the presence of iron (chlorite or silicate) minerals. Most Jasper dates from various geological eras, notably the Mesozoic and Cenozoic.

Uses & applications

Used primarily in lapidary work for cabochons, beads, and decorative carvings. Industrially, it has historically been used for making tools due to its sharp conchoidal fracture.

Geological facts

Jasper was a favorite gemstone in the ancient world; its name can be traced back in Arabic, Persian, Greek, and Latin. Green Jasper specifically was once considered a powerful 'rain-bringer' in medieval folklore.

Field identification & locations

Identify in the field by its opacity (unlike translucent agate), smooth waxy feel, and characteristic shell-like (conchoidal) chips on the edges. Commonly found in riverbeds or coastal areas in regions like Oregon, Idaho, and Madagascar.