sedimentary

Jasper

Silicon dioxide (SiO2) with impurities

Hardness: 6.5-7.0 (Mohs); Color: Dark green with mottled grey/black patches; Luster: Vitreous to waxy; Crystal Structure: Microcrystalline (Trigonal); Cleavage: None; Specific Gravity: 2.58-2.91

Hardness: 6
Color: Dark green with mottled grey/black patches
Luster: Vitreous to waxy

Identified April 9, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7.0 (Mohs); Color: Dark green with mottled grey/black patches; Luster: Vitreous to waxy; Crystal Structure: Microcrystalline (Trigonal); Cleavage: None; Specific Gravity: 2.58-2.91

Formation & geological history

Forms through the deposition of silica from water-rich environments (groundwater or hydrothermal) into tectonic or volcanic cracks. The green color often comes from chlorite or silicate mineral inclusions.

Uses & applications

Commonly used in lapidary work, jewelry (beads, cabochons), carvings, and as a popular collector's stone or polishing material in rock tumblers.

Geological facts

Jasper is an opaque variety of chalcedony. Historically, green jasper was often confused with bloodstone, but it lacks the characteristic red hematite spots. It has been used for seals and amulets since ancient Mesopotamian times.

Field identification & locations

Identify in the field by its smooth, conchoidal (shell-like) fracture and high hardness (it will scratch glass). It frequently occurs as water-worn pebbles in riverbeds or coastal areas alongside other varieties of quartz.