Alpersite
| Alpersite | |
|---|---|
 |
|
| General and classification | |
| other names |
IMA 2003-040 |
| chemical formula | (Mg, Cu) [SO 4 ] • 7H 2 O |
|
Mineral class (and possibly department) |
Sulphates (selenates, tellurates, chromates, molybdates and tungstates) |
|
System no. to Strunz and to Dana |
7.CB.35 ( 8th edition : VI / C.06) 06/29/10/06 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Space group | P 2 1 / c (No. 14) |
| Lattice parameters |
a = 14.166 (4) Å ; b = 6.534 (2) Å; c = 10.838 (3) Å β = 105.922 (6) ° |
| Formula units | Z = 4 |
| Frequent crystal faces | {110}, {001}, {010}, {101} |
| Physical Properties | |
| Mohs hardness | 2.5 |
| Density (g / cm 3 ) | calculated: 1,820 |
| Cleavage | good after {001} |
| Break ; Tenacity | uneven; brittle |
| colour | turquoise blue, greenish blue |
| Line color | White |
| transparency | transparent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.462 n β = 1.465 n γ = 1.469 |
| Birefringence | δ = 0.007 |
| Optical character | biaxial positive |
| Axis angle | 2V = 79 ° (measured), 82 ° (calculated) |
Alpersite is a very rare mineral from the mineral class of "sulfates (and relatives, see classification )" with the chemical composition (Mg, Cu) [SO 4 ] · 7H 2 O. The elements magnesium and copper indicated in the round brackets can be represent each other in the formula , but are always in the same proportion to the other components of the mineral.
Alpersite crystallizes in the monoclinic crystal system and develops isometric, idiomorphic crystals up to about 0.3 mm in size from turquoise blue to greenish blue in color with a glass-like gloss on the surfaces. Alpersit leaves a white line on the marking board . Most of the crystals, which have grown together to form mineral aggregates, can be found in the form of efflorescence and crystal lawns on other minerals. Was also observed in Alpersit ingrown , acicular Pickeringit .
Etymology and history
Alpersite was first discovered in the Big Mike Mine on the south side of Panther Canyon in Pershing County in the US state of Nevada. The sulphide - deposit of volcanic origin was until the 1970s, mainly in copper ores such as bornite , chalcopyrite and Digenite in the sulphide zone and Tenorite and cuprite in the oxidation zone was mined.
The mineral was analyzed and first described by Ronald C. Peterson, Jane M. Hammarstrom and Robert R. Seal II, who named it after the geochemist of the United States Geological Survey Charles N. Alpers, in order to contribute to the understanding of the mineralogical controls of mine water geochemistry to honor. The test results and the chosen name were submitted to the International Mineralogical Association (IMA) for examination in 2003 (IMA's internal entry number: 2003-040 ), which recognized alpersite as a new, independent mineral species. The mineral description was published in 2006 in the science magazine American Mineralogist .
The holotype material is stored in the Canadian Museum of Nature (sample number CNMNC 83921) in a sealed container to avoid drying out.
classification
In the 8th edition of the mineral systematics according to Strunz , which is outdated but still in use , the alpersite belonged to the mineral class of "sulfates, chromates, molybdates, wolframates (including selenates and tellurates)" and there to the department "C. Water-containing sulfates, without foreign anions ”, where together with Bieberite , Boothite , Mallardite , Melanterite and zinc melanterite, the“ Melanterite Group ”with the system no. VI / C.06 .
The 9th edition of Strunz's mineral systematics, which has been in effect since 2001 and is used by the IMA, also classifies alpersite in the category of "sulfates (selenates etc.) without additional anions, with H 2 O". However, this is further subdivided according to the relative size of the cations involved , so that the mineral is classified in the subdivision “B. With only medium-sized cations ”can be found, where the“ melanterite group ”with the system no. Is also found together with Bieberite, Boothite, Mallardite, Melanterite and zinc melanterite. 7.CB.35 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the alpersite to the class of "sulfates, chromates and molybdates" and there in the department of "water-containing acids and sulfates". Here it is also in the " melanterite group (heptahydrate, monoclinic: P 2 1 / c ) " with the system no. June 29, 2010 to be found in the subsection “Water-based acids and sulfates with AXO 4 × x (H 2 O)”.
Chemism
The average, empirical composition Mg 0.58 Cu 0.37 Zn 0.02 Mn 0.02 Fe 0.01 SO 4 · 7H 2 O was determined on the basis of four samples from the Big Mike Mine type locality and contains, in addition to the idealized ones Formula (Mg, Cu) [SO 4 ] · 7H 2 O in addition, small amounts of zinc (Zn), manganese (Mn) and iron (Fe). The small amounts of aluminum (Al) that are also present are attributed to contamination of the samples due to the close connection between Alunogen and Pickeringite .
Crystal structure
Alpersite crystallizes isostructural with melanterite in the monoclinic crystal system in the space group P 2 1 / c (space group no. 14) with the lattice parameters a = 14.166 (4) Å ; b = 6.534 (2) Å; c = 10.838 (3) Å and β = 105.922 (6) ° as well as 4 formula units per unit cell .
Education and Locations
Alpersite is formed from acid mine water in protected areas at a relative humidity of 65% and a temperature of 4 ° C. At its type locality, the Big Mike Mine , which has been closed since the 1970s , the blue alpersite found there was overlaid by a light blue to white and yellowish layer, which consists mainly of Pickeringite , Alunogen , Epsomite and Halotrichite .
As a very rare mineral formation, alpersite is so far (as of 2018) only known in a few samples from less than 10 sites. Its type locality Big Mike Mine in Nevada is the only known site in the United States to date. Within Europe, the mineral was only discovered in Austria, more precisely in the Bärndorfergraben (Prenterwinkelgraben) mining near Bärndorf (Rottenmann municipality) in Styria.
Other well-known sites are the Sherritt Gordon Mine near Sherridon in the Canadian province of Manitoba , the Malanjkhand Mine near Padritola in the Indian state of Madhya Pradesh , the outwash basin at the Cerro Negro and Momotombo volcanoes in the León department of Nicaragua and the Peña de Hierro mine near Nerva (Huelva) in the Spanish region of Andalusia .
See also
literature
- Ronald C. Peterson, Jane M. Hammarstrom, Robert R. Seal II: Alpersite (Mg, Cu) SO 4 · 7H 2 O, a new mineral of the melanterite group, and cuprian pentahydrite: Their occurrence within mine waste . In: American Mineralogist . tape 91 , no. 2–3 , 2006, pp. 261–269 ( rruff.info [PDF; 272 kB ; accessed on April 17, 2018]).
- A. Dominic Fortes, Frank Browning, Ian G. Wood: Cation substitution in synthetic meridianiite (MgSO 4 · 11H 2 O) I: X-ray powder diffraction analysis of quenched polycrystalline aggregates . In: Physics and Chemistry of Minerals . tape 39 , 2012, p. 419-441 .
Web links
- Mineral Atlas: Alpersite (Wiki)
- American-Mineralogist-Crystal-Structure-Database - Alpersite (English)
Individual evidence
- ↑ a b IMA / CNMNC List of Mineral Names; November 2017 (PDF 1.67 MB)
- ↑ a b c Stefan Weiss: The large Lapis mineral directory. All minerals from A - Z and their properties . 6th completely revised and supplemented edition. Weise, Munich 2014, ISBN 978-3-921656-80-8 .
- ↑ a b Webmineral - Alpersite (English)
- ↑ a b c d e f g h i j k l m Ronald C. Peterson, Jane M. Hammarstrom, Robert R. Seal II: Alpersite (Mg, Cu) SO 4 7H 2 O, a new mineral of the melanterite group , and cuprian pentahydrite: Their occurrence within mine waste . In: American Mineralogist . tape 91 , no. 2–3 , 2006, pp. 261–269 ( rruff.info [PDF; 272 kB ; accessed on April 17, 2018]).
- ↑ a b c d e Mindat - Alpersite (English)
- ↑ Find location list for alpersite at the Mineralienatlas and at Mindat