Ganophyllite
| Ganophyllite | |
|---|---|
| General | |
| Category | Mineral |
| Formula (repeating unit) | (K,Na,Ca)2Mn8(Si,Al)12(O,OH)32 · 8H2O |
| Strunz classification | 09.EG.30 |
| Dana classification | 74.01.02.01 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) |
| Space group | A2/a |
| Unit cell | 22,545.01 ų |
| Identification | |
| Formula mass | 1,514.2 |
| Color | Brownish yellow to cinnamon brown |
| Crystal habit | Foliated micaceous |
| Cleavage | {???}Perfect |
| Fracture | Brittle |
| Mohs scale hardness | 4 - 4.5 |
| Luster | Vitreous |
| Streak | Brownish yellow |
| Diaphaneity | Transparent to transculent |
| Specific gravity | 2.84 |
| Density | 2.84 |
| Optical properties | Biaxial(-) |
| Refractive index | nα = 1.537 nβ = 1.611 nγ = 1.613 |
| Birefringence | 0.076 |
| Pleochroism | X = Pale yellow brown
Y = Dark yellow brown Z = Dark yellow brown. |
| Dispersion | Weak |
| Ultraviolet fluorescence | Non-fluorescent |
| Common impurities | Fe, Zn, Pb, Ca, Ba |
| Other characteristics |  Radioactive 3.87% (K) |
Ganophyllite's is a phyllosilicate mineral, which's name came from the greek words leaf (φύλλον) and luster (γανωμα). The latter one is due to the lustrous cleavages. It got named by Axel Hamberg in 1890. It got approved by the IMA in 1959, and it is a grandfathered mineral, meaning its name is still believed to refer to an existing species til this day.[1] Tamaite is the calcium analogue, while eggletonite is the natrium analogue of said mineral.[2]
Properties
It is a member of ganophyllite group, among with eggletonite and tamaite, and it is the potassium variety of eggletonite.[1] The formula includes potassium (K) if it is ganophyllite, eggletonite includes natrium (Na), and tamaite includes calcium (Ca) in their formula. It is pleochroic, which means the gem's color changes depending on the axis it is seen on, which is an optical phenomenon. On the X axis, it is seen in a pale yellow-brown color, and on the Y and Z axis, it can be seen as a dark yellow-brown gem. It has a barely detectable potassium radioactivity. It has a barely detectable 1.8% radiation measured by GRapi (Gamma Ray American Petroleum Institute Units). It mostly consists of oxygen (47.02%), manganese (21.77%) and silicon (16.69%), but otherwise contains aluminium (5.88%), potassium (3.87%), which gives ganophyllite its irradiative attributes, magnesium (2.41%), hydrogen (1.6%) and sodium (0.76%).[3]
Distribution
It can also be found in the Benallt mine as well. Ganophyllite occurs in metamorphosed manganese deposits, especially in zinc-manganese ones. It's a type locality of the Harstigen mine in Sweden, although the first specimen was found iat the Nant mine, Wales.[2] Other finding places include Molinello and Gambatesa mines in Italy, Maple-Hovey deposits in America, at Franklin, New Jersey, at Mont Saint-Hilaire, Canada. Asian mines include the Kumahata mine, the Noda-Tamagawa mine, the Ananai mine, and the Osu and Yonoyama mines, Japan. It can be found at the Broken hill in Australia as well.[4]
Associated minerals
Ganophyllite has a lot of minerals associated with it, although most of it is mine specific. In each mine, the minerals associated with ganophyllite may vary.
In the Harstigen mine, the associated minerals are the followings: pyrophanite, caryopilite, calcite, garnet, rhodonite, barite, lead, and manganoan biotite.
The following associated minerals can occur with specimens from Franklin: axinite, rhodonite, datolite, willemite, roeblingite, bustamite, charlesite and clinohedrite.
Ganophyllites from the Molinello mine have the following associated minerals: caryopilite and parsettensite.[4]
References
- ^ a b "Ganophyllite". www.mindat.org. Retrieved 2021-06-22.
- ^ a b "Mineral Database - Mineralogy of Wales". National Museum Wales. Retrieved 2021-10-18.
- ^ "Ganophyllite Mineral Data". webmineral.com. Retrieved 22 January 2021.
- ^ a b "Ganophyllite" (PDF). Handbook of Mineralogy.
 | This article needs additional or more specific categories. (August 2021) |