Chert
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Mineral NameChert
Chemical FormulaSiO2
Mohs Hardness7
Crystal Systemamorphous
Lusterwaxy
Streak Colorwhite
Cleavagenone
Fractureconchoidal
Specific Gravity2.6
Colorslight brown, tan, grey
Transparencyopaque
Type LocalityBučník, Moravia, Czech Republic
Mineral GroupSilicates
Usesflintknapping, building material, road aggregate
Associated Mineralslimestone, chalk, dolomite
Raritycommon
Description
A light brown to tan, irregularly shaped piece of chert, showing some subtle banding or layering on its surface, with a dull to waxy luster.
Geological Context
Chert is a fine-grained sedimentary rock composed of microcrystalline quartz. It typically forms in marine environments, often as nodules or layers within limestone or chalk, through the accumulation of silica-rich skeletal remains or diagenetic replacement.
