Moganite
Moganite is an oxide mineral with the chemical formula SiO2 (silicon dioxide) that was discovered in 1976. It was initially described as a new form of silica from specimens found in the Barranco de Medio Almud, in the municipality of Mogán on the island of Gran Canaria, in the Canary Islands (Spain), receiving in a later work the name derived from this locality. In 1994 the International Mineralogical Association decided to disapprove it as a valid mineral, since it was considered indistinguishable from quartz. Subsequent studies allowed the IMA to rectify it in 1999, accepting it as a mineral species. It has the same chemical composition as quartz, but a different crystal structure.
| Moganite | |
|---|---|
| General | |
| Category | Tectosilicate, quartz group |
| Formula (repeating unit) | SiO2 |
| IMA symbol | Mog |
| Strunz classification | 4.DA.20 |
| Dana classification | 75.01.04.02 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (same H–M symbol) |
| Space group | I2/a |
| Identification | |
| Color | Grey |
| Crystal habit | Massive |
| Mohs scale hardness | 6 |
| Luster | Earthy, dull |
| Streak | White |
| Diaphaneity | Transparent |
| Specific gravity | 2.52 – 2.58 |
| Optical properties | Biaxial |
| Refractive index | nα = 1.524 nγ = 1.531 |
| References | |
This mineral has been mainly found in dry locales such as Gran Canaria and Lake Magadi. It has been reported from a variety of locations in Europe, India and the United States. Physically, it has a Mohs hardness of about 6, a dull luster and appears as a semitransparent gray in color.