sedimentary
Chert (Lithic flake / Arrowhead fragment)
Microcrystalline Quartz (SiO2)
Hardness: 6.5 to 7 on the Mohs scale. Color: reddish-brown, tan, and greyish-red. Luster: waxy to vitreous. Cleavage: none (exhibits conchoidal fracture). Texture: fine-grained, microcrystalline.
- Hardness
- 6
- Color
- reddish-brown, tan, and greyish-red
- Luster
- waxy to vitreous
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Physical properties
Hardness: 6.5 to 7 on the Mohs scale. Color: reddish-brown, tan, and greyish-red. Luster: waxy to vitreous. Cleavage: none (exhibits conchoidal fracture). Texture: fine-grained, microcrystalline.
Formation & geological history
Chert forms through the accumulation of siliceous oozes or replacement of carbonate minerals in sedimentary environments. This specific piece exhibits flake marks from pressure or percussion flaking, indicating human knapping to produce a lithic tool or projectile point.
Uses & applications
Historically used by indigenous peoples for making sharp tools, scrapers, and arrowheads. Modern specimens are collected as artifacts, geological study material, or lapidary rough.
Geological facts
Small lithic flakes like this are often referred to by archaeologists as debitage—the waste material left over from knapping stone tools. Chert was one of the most widely used rocks in prehistoric human history due to its predictable conchoidal fracturing.
Field identification & locations
Identified by its sharp, worked edges, conchoidal fracturing, waxy luster, and resistance to scratching steel. Commonly found in limestone and dolomite formations or as eroded river cobbles.
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