Mannardite
| Mannardite | |
|---|---|
| General and classification | |
| other names |
IMA 1983-013 |
| chemical formula | Ba (Ti, V, Cr) 8 O 16 · H 2 O |
|
Mineral class (and possibly department) |
Oxides and hydroxides |
|
System no. to Strunz and to Dana |
4.DK.05 ( 8th edition : IV / D.08) 07.09.05.01 |
| Crystallographic Data | |
| Crystal system | tetragonal |
| Crystal class ; symbol | tetragonal-dipyramidal; 4 / m |
| Room group (no.) | I 4 1 / a (No. 88) |
| Lattice parameters | a = 14.36 Å ; c = 5.91 Å |
| Formula units | Z = 4 |
| Physical Properties | |
| Mohs hardness | 5.5 to 7 ( VHN = 609 kg / mm 2 ) |
| Density (g / cm 3 ) | measured: 4.12 to 4.43; calculated: 4.28 |
| Cleavage | good after {100} |
| Break ; Tenacity | uneven to slightly scalloped; brittle |
| colour | black, light reddish brown |
| Line color | white to off-white |
| transparency | opaque |
| shine | Diamond luster |
Mannardite is a very rarely occurring mineral from the mineral class of " oxides and hydroxides ". It crystallizes in the tetragonal crystal system with the chemical composition Ba (Ti, V, Cr) 8 O 16 · H 2 O. The elements titanium , vanadium and chromium in the round brackets can represent each other in the formula ( substitution , diadochy) , but are always in the same proportion to the other components ( barium and crystal water ) of the mineral.
Mannardite is opaque in every form and mostly develops prismatic crystals stretched along the c-axis, jet black in color with white to gray-white streak color . In the reflected light microscope, the mineral also appears light reddish brown. Smooth and unweathered crystal surfaces have a diamond-like sheen .
Etymology and history
Mannardite was first discovered in the "Rough" -grubenfeld ( Rough claims ) on the Kechika River in the north of the Canadian province of British Columbia and described in 1986 by JD Scott and GR Peatfield, who named the mineral after the Canadian geologist George William Mannard (1932-1982) to honor his longstanding work in the field of British Columbia mineralogy and deposits.
classification
In the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , the mannardite belonged to the department of "oxides with the molar ratio metal: oxygen = 1: 2", where it was used together with ankangite , cesàrolite , coronadite , henrymeyerite , hollandite and cryptomelan , Manjiroit , Priderit , Redledgeit and Strontiomelan the "cryptomelan group" with the system no. IV / D.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 classifies mannardite in the category of "Oxides with the molar ratio of metal: oxygen = 1: 2 (and comparable)". However, this is further subdivided according to the relative size of the cations involved and the crystal structure, so that the mineral is classified in the sub-section “With large (± medium-sized) cations; Tunnel structures "can be found where, together with Akaganeit , Coronadit, Henrymeyerit, Hollandit, Manjiroit, Priderit and Redledgeit, the" Hollandit Group "with the system no. 4.DK.05 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns mannardite to the division of "multiple oxides" and the sub-division of the same name. Here you can find him together with Redledgeit in the unnamed group 07.09.05 .
Modifications and varieties
Ankangite (Ba (Ti, V, Cr) 8 O 16 ) was discovered in 1986 by Xiong Ming, Ma Zhesheng and Peng Zhizhong and initially described as an independent mineral that was also recognized by the IMA (IMA No. 1986-026). The mineral was named after the place Ankang in the Chinese province of Shaanxi . In 2012, however, the mineral status was revoked (discredited) and ankangite has been considered an anhydrous variety of mannardite ever since .
Education and Locations
Mannardite in quartz - carbonate veins that cut slate and siltstone was found at its type locality in the "Rough" mine field . In addition to quartz, barite , barytocalcite , norsethite and sulvanite were found as accompanying minerals . In the “Brunswick No. 1 pit, also located near Bathurst in Canada . 12 ”the mineral was found in an ore body in fractured meta sediments together with barytocalcite, edingtonite , harmotome , quartz, siderite and sphalerite .
Other known sites for mannardite so far (as of 2013) are the “Gacun” mine near Maqiong ( Baiyü district ) in the northwest of the Chinese province of Sichuan and the “Star” mine near Theunissen in the South African district of Lejweleputswa .
Crystal structure
Mannardite crystallizes tetragonally in the space group I 4 1 / a (space group no. 88) with the lattice parameters a = 14.36 Å and c = 5.91 Å as well as 4 formula units per unit cell .
literature
- JD Scott, GR Peatfield: Mannardite [Ba · H2O] (Ti6V3 + 2) O16, a new mineral species, and new data on redledgeite , in: The Canadian Mineralogist , Volume 24 (1986), pp. 55-66 ( PDF 1 , 5 MB )
See also
Web links
Individual evidence
- ↑ a b c d e 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. 226 .
- ↑ Webmineral - Mannardite
- ↑ a b c d Mannardite , in: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 69.7 kB )
- ↑ Cristian Biagioni, Carmen Capalbo, Marco Pasero: Nomenclature tunings in the hollandite supergroup , in: European Journal of Mineralogy , Volume 25, No. 1, February 2013, pp. 85–90 (6) doi : 10.1127 / 0935-1221 / 2013 / 0025-2255
- ^ Mindat - Mannardite