sedimentary

Jasper with Chert

Silicon Dioxide (SiO2) - Microcrystalline Quartz

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs scale), Color: Variegated yellow, cream, and red (likely from iron oxides), Luster: Dull to waxy, Crystal Structure: Hexagonal (Microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.6-2.9

Hardness: 6

Identified April 6, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from the deposition of silica in sedimentary environments, often replacing organic materials or filling cavities in volcanic rocks. The colors are due to mineral impurities like hematite (red) and goethite (yellow).

Uses & applications

Used primarily in lapidary arts for polishing, jewelry (cabochons), or as garden decorative stones. Historically used for making tools and arrowheads due to its conchoidal fracture.

Geological facts

Jasper is a variety of chalcedony. The red spots in this specimen are characteristic of jasper, while the tan, opaque areas are often referred to as common chert or jasperite depending on the region of origin.

Field identification & locations

Identify in the field by its inability to be scratched by a steel knife, its smooth waxy feel, and the way it breaks in curved, shell-like patterns. Commonly found in riverbeds and glacial till throughout North America.