Jasper Chert Nodules

Physical Properties

Hardness: 6.5-7 (Mohs scale); Color: Red, brown, and tan; Luster: Waxy to dull; Crystal structure: Microcrystalline/Cryptocrystalline quartz; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.9

Formation & Geological History

Formed through the precipitation of silica in sedimentary rock layers or as nodules in limestone/chalk. The red coloration is typically due to the presence of iron oxide (hematite).

Uses & Applications

Used primarily in lapidary work for cabochons and jewelry, as well as for stone tools (flintknapping) historically, and as decorative gravel.

Geological Facts

Jasper and chert have been used for millennia to create sharp tools and arrowheads because of their conchoidal fracture pattern, which creates razor-sharp edges.

Field Identification & Locations

Identify in the field by its smooth, waxy interior and sharp, glass-like fracture edges when broken. It is often found in riverbeds or within sedimentary cliff faces.

Identified on: 4/22/2026

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