sedimentary
Chalk
Calcium Carbonate (CaCO3)
AI-generated identification · may be incorrectMohs hardness of 1, white or light gray color, dull or earthy luster, microcrystalline structure, conchoidal fracture.
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Physical properties
Mohs hardness of 1, white or light gray color, dull or earthy luster, microcrystalline structure, conchoidal fracture.
Formation & geological history
Formed from the accumulation of microscopic calcareous skeletal remains of marine phytoplankton called coccolithophores during the Cretaceous period.
Uses & applications
Used in agriculture for soil pH balancing, manufacturing of lime and cement, writing implements, and athletic grip.
Geological facts
Famous chalk deposits include the iconic White Cliffs of Dover in England, formed over millions of years.
Field identification & locations
Easily identified by its soft, powdery texture and vigorous effervescence when treated with dilute hydrochloric acid.
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Sandstone or Siltstone
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Shale
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Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
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