mineral
Calcite on Limestone
Calcium Carbonate (CaCO3) on Sedimentary Rock
Hardness: 3 (Mohs scale), Color: tan to creamy white crystals on reddish-brown matrix, Luster: vitreous to pearly, Crystal structure: rhombohedral or scalenohedral, Cleavage: perfect rhombohedral
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Physical properties
Hardness: 3 (Mohs scale), Color: tan to creamy white crystals on reddish-brown matrix, Luster: vitreous to pearly, Crystal structure: rhombohedral or scalenohedral, Cleavage: perfect rhombohedral
Formation & geological history
Forms through chemical precipitation in sedimentary environments or hydrothermal veins. This specimen likely formed as groundwater rich in calcium carbonate filled fractures or cavities in limestone, allowing crystals to grow over time.
Uses & applications
Primarily collected as mineral specimens; limestone matrix is used in construction and cement production.
Geological facts
Calcite is one of the most common and varied minerals on Earth. It is the primary component of stalactites and stalagmites in caves and shows strong double refraction in clear varieties.
Field identification & locations
Identify by its 3.0 hardness (can be scratched by a copper penny) and its vigorous effervescence (bubbling) when exposed to cold dilute hydrochloric acid or strong vinegar. Found commonly in limestone quarries and road cuts.
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