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Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO 3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on the Mohs scale of mineral hardness, based on scratch hardness comparison. Large calcite crystals are used in optical equipment, and limestone composed ...
English: Exhibit in the Natural History Museum of Utah, Salt Lake City, Utah, USA. This item is old enough so that it is in the public domain. Photography was permitted in the museum without restriction.
Tabulata, commonly known as tabulate corals, are an order of extinct forms of coral.They are almost always colonial, forming colonies of individual hexagonal cells known as corallites defined by a skeleton of calcite, similar in appearance to a honeycomb.
The skeleton has either a mesh or honeycomb structure of interlocking spicules. [3] Some extinct species were hypercalcified, meaning that the spicule-based skeleton is cemented together by solid calcite.
Boxwork in Wind Cave, South Dakota. In geology, boxwork is defined as a honeycomb-like structure that can form in some fractured or jointed sedimentary rocks. If the fractures in the host rock are mineralized, they can become more resistant to weathering than the surrounding rock, and subsequent erosion can produce boxwork structures.
Honeycomb weathering, also known as honeycombs, honeycombed sandstone, is a form of cavernous weathering that consists of regular, tightly adjoining, and commonly patterned cavities that are developed in weathered bedrock; are less than 2 cm (0.79 in) in size; and resemble a honeycombed structure.
A cave pearl is composed primarily of calcite (calcium carbonate [CaCO 3]). Cave pearls are generally not considered to be a type of oolite. Other minerals found in small quantities in cave pearls include quartz (silicon dioxide [SiO 2]), apatite (a group of phosphate minerals), iron, aluminium, and magnesium. [1] [2]
A hypothesis of growth by accretion (like a snowball) from the polymineralic sediment of fine aragonite, high-magnesium calcite (HMC) and low-magnesium calcite (LMC), must explain how only aragonite needles are added to the ooid cortex. Both in tangential and in radial ooids, the cortex is composed of many very fine increments of growth.