sedimentary

Red Jasper (Chert)

Silicon dioxide with iron inclusions (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs); Color: Deep red to reddish-brown; Luster: Dull to vitreous; Crystal Structure: Trigonal (Microcrystalline); Cleavage: None (Conchoidal fracture); Specific Gravity: 2.58-2.91

Hardness: 6
Color: Deep red to reddish-brown
Luster: Dull to vitreous

Identified July 19, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (Mohs); Color: Deep red to reddish-brown; Luster: Dull to vitreous; Crystal Structure: Trigonal (Microcrystalline); Cleavage: None (Conchoidal fracture); Specific Gravity: 2.58-2.91

Formation & geological history

Formed through the accumulation of silica-rich microfossils or precipitation of silica in volcanic or sedimentary environments, often associated with banded iron formations or hydrothermal fluids.

Uses & applications

Commonly used as a gemstone for jewelry, lapidary carvings, decorative ornaments, and historically for making sharp stone tools like scrapers and arrowheads due to its conchoidal fracture.

Geological facts

Red Jasper has been used since ancient times for amulets and seals; the red color is caused specifically by inclusions of hematite (iron oxide).

Field identification & locations

Identify by its waxy to dull luster, extreme hardness (scratches glass), and characteristic shell-like (conchoidal) breakage patterns. Found widely in riverbeds or gravel pits in areas with ancient seafloors or volcanic activity.