sedimentary

Red Jasper (Siltstone/Quartz variety)

Silicon Dioxide (SiO2) with Hematite impurities

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs scale); Color: Opaque reddish-brown to terracotta; Luster: Dull to waxy when unpolished; Structure: Microcrystalline/Cryptocrystalline quartz; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91

Hardness: 6
Color: Opaque reddish-brown to terracotta
Luster: Dull to waxy when unpolished

Identified March 24, 2026More sedimentary →

Explore Red Jasper (Siltstone/Quartz variety) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed through the accumulation of fine-grained silica sediment (often from volcanic ash or radiolarian remains) that becomes saturated with iron oxide (hematite) during diagenesis. Frequently found as water-worn pebbles in riverbeds or beaches.

Uses & applications

Used primarily for lapidary work, jewelry (beads, cabochons), ornamental mosaics, and as a popular 'pocket stone' for collectors and metaphysical practitioners.

Geological facts

Jasper has been used for thousands of years; in ancient times, it was often referred to as 'the mother of all stones.' The red color is caused specifically by iron inclusions within the quartz matrix.

Field identification & locations

Identify in the field by its opacity (will not let light through even at thin edges) and its smooth, rounded river-worn texture. Commonly found in areas with ancient volcanic activity or gravel deposits such as the Pacific Northwest, USA and parts of India and Brazil.