Carpholite is a manganese

silicate mineral Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust. In mineralogy, the crystalline forms of silica (silicon dio ...

with formula Mn²⁺Al₂Si₂O₆(OH)₄. It occurs as yellow clusters of slender prisms or needles. It crystallizes in the

orthorhombic In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic Lattice (group), lattices result from stretching a cubic crystal system, cubic lattice along two of its orthogonal pairs by two different factors, res ...

system. The carpholite group includes ferrocarpholite, magnesiocarpholite,

vanadiocarpholite Vanadiocarpholite (Mn2+V3+AlSi2O6(OH)4) is straw yellow to brown silicate mineral. It crystallizes in the orthorhombic crystal system. It is the vanadium rich variety of carpholite (Mn2+Al2Si2O6(OH)4). Discovery and occurrence It was first descr ...

, and potassiccarpholite.

Discovery and occurrence

It was first described in 1817 for an occurrence in Horní Slavkov ( Schlaggenwald),

Karlovy Vary Region The Karlovy Vary Region () is an administrative unit () of the Czech Republic, located in the westernmost part of the country. It is named after its capital Karlovy Vary. It is known for spas, which include Karlovy Vary and Mariánské Lázně. ...

Bohemia Bohemia ( ; ; ) is the westernmost and largest historical region of the Czech Republic. In a narrow, geographic sense, it roughly encompasses the territories of present-day Czechia that fall within the Elbe River's drainage basin, but historic ...

. The name derives from Greek ''karfos'' for "straw" and ''lithos'' for "stone" due to its

crystal habit In mineralogy, crystal habit is the characteristic external shape of an individual crystal or aggregate of crystals. The habit of a crystal is dependent on its crystallographic form and growth conditions, which generally creates irregularities d ...

. Its typical occurrence is in

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of Clay mineral, clay minerals (hydrous aluminium phyllosilicates, e.g., Kaolinite, kaolin, aluminium, Al2Silicon, Si2Oxygen, O5(hydroxide, OH)4) and tiny f ...

s that have undergone low grade

metamorphism Metamorphism is the transformation of existing Rock (geology), rock (the protolith) to rock with a different mineral composition or Texture (geology), texture. Metamorphism takes place at temperatures in excess of , and often also at elevated ...

. Associated minerals include

sudoite Sudoite is a mineral from the chlorite group. It was named after Toshio Sudo (1911-2000), professor of mineralogy at the University of Tokyo, in Japan, and a pioneer of clay science. The mineral tosudite also bears his name. It was approved as a ...

, manganoan

garnet Garnets () are a group of silicate minerals that have been used since the Bronze Age as gemstones and abrasives. Garnet minerals, while sharing similar physical and crystallographic properties, exhibit a wide range of chemical compositions, de ...

chloritoid Chloritoid is a silicate mineral of metamorphic origin. It is an iron magnesium manganese alumino-silicate hydroxide with formula . It occurs as greenish grey to black platy micaceous crystals and foliated masses. Its Mohs hardness is 6.5, unusual ...

and

fluorite Fluorite (also called fluorspar) is the mineral form of calcium fluoride, CaF2. It belongs to the halide minerals. It crystallizes in isometric cubic habit, although octahedral and more complex isometric forms are not uncommon. The Mohs scal ...

References

Inosilicates Orthorhombic minerals Minerals in space group 68 {{silicate-mineral-stub