Henritermierite
| Henritermierite | |
|---|---|
 |
|
| General and classification | |
| other names |
IMA 1968-029 |
| chemical formula |
|
|
Mineral class (and possibly department) |
Silicates and Germanates |
|
System no. to Strunz and to Dana |
9.AD.25 ( 8th edition : VIII / A.08) April 51, April 01 |
| Crystallographic Data | |
| Crystal system | tetragonal |
| Crystal class ; symbol | ditetragonal-dipyramidal; 4 / m 2 / m 2 / m |
| Room group (no.) | I 4 1 / acd (No. 142) |
| Lattice parameters | a = 12.39 Å ; c = 11.91 Å |
| Formula units | Z = 8 |
| Twinning | after {101} |
| Physical Properties | |
| Mohs hardness | not defined |
| Density (g / cm 3 ) | measured: 3.34 (2); calculated: 3.40 |
| Cleavage | no |
| Break ; Tenacity | shell-like |
| colour | “Clove brown” to “apricot colored”, lemon yellow to light yellow |
| Line color | White |
| transparency | translucent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n ω = 1.765 n ε = 1.800 |
| Birefringence | δ = 0.035 |
| Optical character | uniaxial positive |
| Pleochroism | weak: ω = very light yellow, ε = lemon yellow |
Henritermierite is a very rare mineral from the group of garnets within the mineral class of " silicates and germanates ". It crystallizes in the tetragonal crystal system with the idealized chemical composition Ca 3 Mn 3+ 2 [(SiO 4 ) 2 (OH) 4 ], so it is chemically a calcium - manganese - hydrogarnet . Structurally, like the other grenades, it belongs to the island silicates .
Since Henritermierit with Grossular (Ca 3 Al 2 [SiO 4 ] 3 ) a complete solid solution forms and, therefore, usually a small proportion of manganese by aluminum replaced is, the chemical formula for Henritermierit generally with Ca 3 (Mn 3+ , Al) 2 [(SiO 4 ) 2 (OH) 4 ]. In addition, the mineral forms mixed series with katoite (Ca 3 Al 2 [(SiO 4 ) > 1.5 ((OH) 4 ) <1.5 ]) and hydro-andradite . Due to the mixed crystal formation, the color of Henritermierite varies from “clove brown” to “apricot color” or lemon yellow to light yellow.
The mineral usually develops translucent crystals with a short prismatic or pseudo- octahedral habit , but can also be found in the form of granular mineral aggregates .
Etymology and history
Henritermierite was discovered in the "Tachgagalt" open pit mine in the Moroccan province of Ouarzazate and described by C. Gaudefroy, M. Orliac, F. Permingeate, A. Parfenoff, who named the mineral after the French geologist Henri François Émile Termier (1897–1989).
classification
The structural classification of the International Mineralogical Association (IMA) counts the henritermierite to the garnet upper group, where together with holtstamite it forms the henritermierite group with 8 positive charges on the tetrahedrally coordinated lattice position. Formally, the Montenevin also belongs to this group, although structurally and chemically it is closer to the minerals of the Bitikleit group.
Already in the meanwhile outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the henritermierite belonged to the mineral class of "silicates and germanates" and there to the department of " island silicates (nesosilicates)", where together with almandine , andradite , calderite , Goldmanit , Grossular , Hibschite , Holtstamit , Hydrougrandit , katoite , Kimzeyit , Knorringit , majorite , Morimotoit , Pyrop , Schorlomit , Spessartin , Uwarowit , wadalite and Yamatoit (discredited because identical to Momoiit ) the "garnet group" with the system number. VIII / A.08 .
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also assigns henritermierite to the class of “silicates and germanates” and there to the “island silicates (nesosilicates)” category. This section is further subdivided according to the possible presence of further anions as well as the coordination of the cations involved , so that the mineral can be classified according to its composition and structure in the subdivision of “island silicates without further anions; Cations in octahedral [6] and usually greater coordination "can be found, where together with almandine, andradite, calderite, goldmanite, grossular, holtstamite, katoite, kimzeyite, knorringite, majorite, morimotoite, pyrope, schorlomite, spessartine and uwarowite the" Garnet group "with the system no. 9.AD.25 forms. The garnet compounds blythite, hibschite, hydroandradite and skiagite, which are no longer regarded as minerals, were also included in this group. Wadalite , at that time still grouped with the grenades, proved to be structurally different and is now assigned to a separate group with chloromayenite and fluoromayenite . The garnets irinarassite , hutcheonite , kerimasite , toturite , menzerite (Y) and eringaite described after 2001 would have been classified in the garnet group.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Henritermierite to the class of "silicates and Germanates" and there to the department of "island silicate minerals ". Here it is together with Holtstamit in the " Garnet Group (Tetragonal Hydrogranate) " with the system no. April 51, 2004 to be found in the subsection “ Island silicates: SiO 4 groups only with cations in [6] and> [6] coordination”.
Education and Locations
Henritermierite forms in manganese-rich ore deposits. At its type locality "Tachgagalt" it was found in the form of small grains that filled in the gaps between the crystals of other minerals. Calcite , Gaudefroyite , Hausmannite and Morocite appeared here as accompanying minerals .
Furthermore, so far (as of 2013) the mineral could only be found in the "N'Chwaning Mine" near Kuruman and in the "Wessels Mine" near Hotazel in the Kalahari manganese field in South Africa, where it is mixed with andradite , barite , calcite, Hematite , hausmannite and manganite appeared together.
Crystal structure
Henritermierite crystallizes tetragonally in the space group I 4 1 / acd (space group no. 142) with the lattice parameters a = 12.39 Å and c = 11.91 Å as well as 8 formula units per unit cell .
See also
literature
- C. Gaudefroy, M. Orliac, F. Permingeat, A. Parfenoff: L'henritermiérite, une nouvelle espèce minérale , In: Bulletin de la Société Française de Minéralogie et de Cristallographie , Volume 92 (1969), pp. 185-190 ( PDF 459.4 kB )
- T. Armbruster, T. Kohler, E. Libowitzky, A. Friedrich, R. Miletich, M. Kunz, O. Medenbach, J. Gutzmer: Structure, compressibility, hydrogen bonding, and dehydration of the tetragonal Mn 3+ hydrogarnet, henritermierite , In: American Mineralogist , Volume 86 (2001), pp. 147–158 ( PDF 410 kB )
- Maximilian Glas et al .: Garnet . In: Christian Weise (ed.): ExtraLapis . tape 9 . Christian Weise Verlag, 1995, ISBN 3-921656-35-4 , ISSN 0945-8492 , p. 5 .
- Friedrich Klockmann : Klockmann's textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke , Stuttgart 1978, ISBN 3-432-82986-8 , pp. 669 (first edition: 1891).
Web links
Individual evidence
- ↑ a b IMA / CNMNC List of Mineral Names; February 2013 (PDF; 1.4 MB)
- ↑ a b c d e f g Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 541-542 .
- ↑ Webmineral - Henritermierite
- ↑ a b c Henritermierite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 72 kB )
- ↑ a b Mindat - Henritermierite
- ^ A b Edward S. Grew, Andrew J. Locock, Stuart J. Mills, Irina O. Galuskina, Evgeny V. Galuskin and Ulf Hålenius: IMA Report - Nomenclature of the garnet supergroup . In: The American Mineralogist . tape 98 , 2013, p. 785–811 ( main.jp [PDF; 2,3 MB ; accessed on July 8, 2017]).
- ↑ Find location list for Henritermierite at the Mineralienatlas and at Mindat