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Cleavage is a physical property traditionally used in mineral identification, both in hand-sized specimen and microscopic examination of rock and mineral studies. As an example, the angles between the prismatic cleavage planes for the pyroxenes (88–92°) and the amphiboles (56–124°) are diagnostic.
Spaced cleavage occurs in rocks with minerals that are not evenly distributed, and as a result the rock forms discontinuous layers or lenses of different types of minerals. [1] Spaced cleavage contains two types of domains; cleavage domains and microlithons. Cleavage domains are planar boundaries subparallel to the trend of the domain, and ...
Wet-ground mica, which retains the brilliance of its cleavage faces, is used primarily in pearlescent paints by the automotive industry. Many metallic-looking pigments are composed of a substrate of mica coated with another mineral, usually titanium dioxide (TiO 2). The resultant pigment produces a reflective color depending on the thickness of ...
Orthoclase, or orthoclase feldspar (endmember formula K Al Si 3 O 8), is an important tectosilicate mineral which forms igneous rock.The name is from the Ancient Greek for "straight fracture", because its two cleavage planes are at right angles to each other.
Two-directional cleavage is described as prismatic, and occurs in minerals such as the amphiboles and pyroxenes. Minerals such as galena or halite have cubic (or isometric) cleavage in three directions, at 90°; when three directions of cleavage are present, but not at 90°, such as in calcite or rhodochrosite, it
Sphalerite possesses perfect dodecahedral cleavage, having six cleavage planes. [10] [18] In pure form, it is a semiconductor, but transitions to a conductor as the iron content increases. [19] It has a hardness of 3.5 to 4 on the Mohs scale of mineral hardness. [20]
Hornblende is most often confused with the pyroxene series and biotite mica, which are also dark minerals found in granite and charnockite. Pyroxenes differ in their cleavage planes, which intersect at 87° and 93°. [8] Hornblende is an inosilicate (chain silicate) mineral, built around double chains of silica tetrahedra.
Muscovite (also known as common mica, isinglass, or potash mica [6]) is a hydrated phyllosilicate mineral of aluminium and potassium with formula KAl 2 (AlSi 3 O 10)(F,OH) 2, or 2 (Al 2 O 3) 3 (SiO 2) 6 (H 2 O). It has a highly perfect basal cleavage yielding remarkably thin laminae (sheets) which are often highly elastic.