Moganite is a silicate mineral with the chemical formula Si
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...

Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

2 (silicon dioxide
Silicon dioxide
The chemical compound silicon dioxide, also known as silica , is an oxide of silicon with the chemical formula '. It has been known for its hardness since antiquity...

) that was discovered in 1984. It crystallises in the monoclinic crystal system
Monoclinic crystal system
In crystallography, the monoclinic crystal system is one of the 7 lattice point groups. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal length, as in the orthorhombic system. They form a rectangular prism with a...

. Moganite is considered a polymorph
Polymorphism (materials science)
Polymorphism in materials science is the ability of a solid material to exist in more than one form or crystal structure. Polymorphism can potentially be found in any crystalline material including polymers, minerals, and metals, and is related to allotropy, which refers to chemical elements...

 of quartz
Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...

: it has the same chemical composition as quartz, but a different crystal structure.

In 1994, the International Mineralogical Association
International Mineralogical Association
The International Mineralogical Association is an international group of 38 national societies. The goal is to promote the science of mineralogy and to standardize the nomenclature of the 4000 plus known mineral species...

 (IMA) had disapproved it as being a separate species because it was not clearly distinguishable from quartz. It has only recently been approved as a valid species by the CNMNC, the Commission on New Minerals, Nomenclature and Classification (part of the IMA).
This mineral is “virtually indistinguishable” from chalcedony
Chalcedony is a cryptocrystalline form of silica, composed of very fine intergrowths of the minerals quartz and moganite. These are both silica minerals, but they differ in that quartz has a trigonal crystal structure, while moganite is monoclinic...

 which is made up of both moganite and quartz. It has been mainly found in dry locales such as Gran Canaria
Gran Canaria
Gran Canaria is the second most populous island of the Canary Islands, with a population of 838,397 which constitutes approximately 40% of the population of the archipelago...

 and Lake Magadi
Lake Magadi
Lake Magadi is the southernmost lake in the Kenya Rift Valley, lying in a catchment of faulted volcanic rocks, north of Tanzania's Lake Natron. During the dry season, it is 80% covered by soda and is well known for its wading birds, including flamingos....

. It has been reported from a variety of locations in Europe, India and the United States. It was named for the municipality of Mogán on Gran Canaria. Physically, it has a hardness of about 6, a dull luster and appears gray in color but transparent.

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