Xocolatlite
| Xocolatlite | |
|---|---|
 |
|
| General and classification | |
| other names |
IMA 2007-020 |
| chemical formula | Ca 2 Mn 2 4+ Te 2 6+ O 12 • H 2 O |
|
Mineral class (and possibly department) |
Sulphates (selenates, tellurates, chromates, molybdates, tungstates) |
|
System no. to Strunz and to Dana |
7.DF.85 33.02.10.01 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Space group | P 2 (No. 3) , P 2 / m (No. 10) or Pm (No. 6) |
| Lattice parameters |
a = 10.757 Å ; b = 4.928 Å; c = 8.942 Å β = 102.39 ° |
| Formula units | Z = 2 |
| Physical Properties | |
| Mohs hardness | 2 to 3 |
| Density (g / cm 3 ) | calculated: 4.97 |
| Cleavage | perfect (mica-like) |
| Break ; Tenacity | shell-like |
| colour | chocolate brown |
| Line color | copper brown |
| transparency | transparent |
| shine | Glass gloss |
Xocolatlite is a very rarely occurring mineral from the mineral class of "sulfates (including selenates, tellurates, chromates, molybdates, wolframates)". It crystallizes in the monoclinic crystal system with the chemical composition Ca 2 Mn 2 4+ Te 2 6+ O 12 · H 2 O and is therefore a water-containing calcium - manganese - tellurate .
Xocolatlit usually develops leafy and spherical mineral aggregates or crusty coatings of chocolate-brown color with a copper-brown streak color .
Etymology and history
Xocolatlit was first discovered in 2002 in the Moctezuma Mine (Bambolla Mine) near Moctezuma in the Mexican state of Sonora and described in 2008 by Pascal V. Grundler, Joël Brugger, Nicolas Meisser, Stefan Ansermet, Stacey Borg, Barbara Etschmann, Denis Testemale and Trudy Bolin, the named the mineral after the name of the first cocoa-containing drink because of its color and origin .
With xocóatl or xocólatl [ ʃokolaːtɬ ] ( Nahuatl xócoc 'bitter' , atl 'water'; also 'bitter water' or 'cocoa water') the Aztecs in Mexico referred to a mixture of water, cocoa, corn , vanilla and cayenne pepper (see also History of Cocoa ).
classification
Since the Xocolatlite was only discovered in 2002 and only confirmed by the International Mineralogical Association (IMA) in 2007 , it is not listed in the Strunz mineral system (8th edition), which has been outdated since 2001 .
The 9th edition of Strunz's mineral systematics , which has been in effect since that time and is used by the IMA, assigns xocolatlite to the class of "sulfates (selenates, tellurates, chromates, molybdates, wolframates)" and then to the department of "sulfates (selenates, etc.)" .) with additional anions , with H 2 O “. This section is further subdivided according to the size of the cations involved , so that the mineral can be found according to its composition in the sub-section “With large and medium-sized cations”, where it is the only member of the unnamed group 7.DF.85 .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns xocolatlite to the class of "sulfates, chromates and molybdates" and there to the " selenates and tellurates " class. Here he is the only member of the unnamed group 02.33.10 within the subsection “ Selenates and Tellurates with A + (B 2+ ) m XO 6 Z q × x (H 2 O), x can be equal to 0 ”.
Crystal structure
Xocolatlite crystallizes monoclinically in the space group P 2 (space group no. 3) , P 2 / m (no. 10) or Pm (no. 6) with the lattice parameters a = 10.757 Å ; b = 4.928 Å; c = 8.942 Å and β = 102.39 ° and 2 formula units per unit cell .
Education and Locations
Xocolatlite found mostly in the form of crusty coatings on quartz , but can also Schmitterit , jarosite , Eztlit , Emmonsit or barite associated occur.
The only known site to date is its type locality Moctezuma Mine in Sonora, Mexico.
See also
literature
- Pascal V. Grundler, Joël Brugger, Nicolas Meisser, Stefan Ansermet, Stacey Borg, Barbara Etschmann, Denis Testemale, Trudy Bolin: Xocolatlite, Ca2Mn42 + Te2O12 H2O, a new tellurate related to kuranakhite: Description and measurement of Te oxidation state by XANES spectroscopy (PDF; 843 kB), in: American Mineralogist , Volume 93, pages 1911–1920, 2008
Web links
Individual evidence
- ↑ a b Pascal V. Grundler, Joël Brugger, Nicolas Meisser, Stefan Ansermet, Stacey Borg, Barbara Etschmann, Denis Testemale, Trudy Bolin: Xocolatlite, Ca2Mn42 + Te2O12 H2O, a new tellurate related to kuranakhite: Description and measurement of Te oxidation state by XANES spectroscopy (PDF; 843 kB), in: American Mineralogist , Volume 93, pages 1911–1920, 2008
- ↑ a b Mindat - Xocolatlite
- ↑ See Online Etymology Dictionary: chocolate