sedimentary

Yellow-brown chert or jasper

Microcrystalline quartz (SiO₂), likely iron-oxide-bearing chert/jasper

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; mustard yellow to brown, opaque, waxy-to-dull luster, very fine-grained cryptocrystalline quartz, and conchoidal fracture. Dark veins and gray-white margins may represent iron/manganese oxides and weathered host material.

Identified September 15, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when silica-rich fluids replace or cement fine sediment, commonly as nodules or beds; coloration comes mainly from iron oxides. The specimen’s precise geological age cannot be determined from the image and depends on its host formation.

Uses & applications

Used as decorative stone, cabochons, beads, carvings, and occasionally aggregate; attractive pieces have modest lapidary value.

Geological facts

Jasper is technically an opaque, impure variety of chert. Its smooth curved fractures and lack of visible crystals help distinguish it from most crystalline igneous rocks.

Field identification & locations

Test for glass-scratching hardness and inspect a fresh fracture for a smooth, waxy surface; avoid relying on color alone. Common worldwide, especially in sedimentary and volcanic terrains.