Flint nodule with cortex found in the flint mines of Rijckholt-Sint Geertruid, Netherlands, 4500-3000 BC. Collection Stichting ir. D.C. van Schaïk, Maastricht — Photo: Arjuno3 · CC BY-SA 4.0
Flint
Also known as: Chert.
The cryptocrystalline quartz of chalk and limestone beds — humankind's original toolstone and fire-starter.
Intro adapted from Wikipedia (CC BY-SA).
Flint is a rock-forming material, with the chemical formula SiO₂ (cryptocrystalline).
It crystallizes in the trigonal crystal system.
Key properties: Mohs hardness 7; typically gray or black or brown.
Collections: Everyday Minerals.
Index entry. This entry combines official IMA/RRUFF species data with published physical-property data and a Wikipedia introduction — a full written entry hasn’t been published yet.
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