sedimentary
Chert
Silicon dioxide (SiO2) - Microcrystalline quartz
AI-generated identification · may be incorrectHardness of 6.5-7 on the Mohs scale. Colors vary widely, often gray, brown, black, or red. Luster is waxy to dull. Crystal structure is microcrystalline. Exhibits conchoidal fracture. Specific gravity is 2.59-2.65.
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Physical properties
Hardness of 6.5-7 on the Mohs scale. Colors vary widely, often gray, brown, black, or red. Luster is waxy to dull. Crystal structure is microcrystalline. Exhibits conchoidal fracture. Specific gravity is 2.59-2.65.
Formation & geological history
Forms as nodules in sedimentary rocks, typically limestone, or as bedded deposits. Formed from the accumulation of siliceous skeletons of microscopic organisms or by chemical precipitation. Can be of various geological ages.
Uses & applications
Historically used for making stone tools (arrowheads, scrapers) due to its conchoidal fracture. Sometimes used as a road surfacing material or in construction. Collectible as artifacts or lapidary material.
Geological facts
Flint is a dark variety of chert. Jasper is an opaque, often red variety. Chert was crucial for early human survival for tool making and fire starting.
Field identification & locations
Identify by its hardness (scratches glass), waxy luster, and conchoidal fracture. Commonly found in sedimentary basins worldwide. Tips for collectors: look for nodules in limestone or stream beds.
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