sedimentary

Chert (Jasper/Agate mix)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs scale); Color: Red, white, and grayish-blue; Luster: Waxy to vitreous; Structure: Microcrystalline/cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.65

Hardness: 6
Color: Red, white, and grayish-blue
Luster: Waxy to vitreous

Identified June 15, 2026More sedimentary →

Explore Chert (Jasper/Agate mix) 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 via the accumulation of silica-rich fluids or microscopic organic remains (like radiolarians) that undergo lithification. This specimen likely formed as a nodule in limestone or through hydrothermal deposition in volcanic cavities.

Uses & applications

Commonly used for lapidary work (jewelry, cabochons), flint-knapping for stone tools (arrowheads), and as a collector's specimen. In industry, crushed chert is used for road surfacing.

Geological facts

Chert has been used by humans for millions of years to create tools because it breaks with sharp, predictable edges. This specific red and white variety is often called 'Jasper' if opaque or 'Agate' if translucent.

Field identification & locations

Identify in the field by its smooth, shell-like (conchoidal) fracture and its ability to scratch glass. It is commonly found in sedimentary rock beds or as river-worn cobbles.