sedimentary
Flint
Silicon Dioxide (SiO2) - Cryptocrystalline Quartz
Hardness: 7 on the Mohs scale. Color: Dark gray, black, or brownish-gray. Luster: Waxy to dull. Fracture: Conchoidal with sharp edges. Microcrystalline structure.
- Hardness
- 7 on the Mohs scale
- Color
- Dark gray, black, or brownish-gray
- Luster
- Waxy to dull
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Physical properties
Hardness: 7 on the Mohs scale. Color: Dark gray, black, or brownish-gray. Luster: Waxy to dull. Fracture: Conchoidal with sharp edges. Microcrystalline structure.
Formation & geological history
Formed as nodules within sedimentary rocks like chalk or limestone through the precipitation of microcrystalline silica, often derived from the skeletal remains of sponges and radiolarians.
Uses & applications
Historically used for stone tools, arrowheads, and spark-striking flintlocks. Currently used in road construction, ceramics, and as a decorative stone.
Geological facts
Flint was one of the most vital raw materials for early humans during the Stone Age due to its ability to split into exceptionally sharp blades.
Field identification & locations
Identified by its dark gray to black color, smooth waxy surface, and characteristic curved, shell-like (conchoidal) fracture pattern. Commonly found in coastal chalk cliffs and sedimentary gravels.
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