Melanovanadite
| Melanovanadite | |
|---|---|
| General and classification | |
| chemical formula |
|
|
Mineral class (and possibly department) |
Oxides and hydroxides (including V [5,6] vanadates, arsenites, antimonites, bismutites, sulfites, selenites, tellurites, iodates) - vanadium oxides |
|
System no. to Strunz and to Dana |
4.HE.05 ( 8th edition : IV / G.10) 47.03.06.01 |
| Similar minerals | Duttonite |
| Crystallographic Data | |
| Crystal system | triclinic |
| Crystal class ; symbol | triclinic pinacoidal; 1 |
| Space group | P 1 (No. 2) |
| Lattice parameters |
a = 6.36 Å ; b = 18.09 Å; c = 6.28 Å α = 110.2 °; β = 101.6 °; γ = 82.9 ° |
| Formula units | Z = 2 |
| Physical Properties | |
| Mohs hardness | 2.5 |
| Density (g / cm 3 ) | measured: 2.55; calculated: 2.53 |
| Cleavage | completely after {010} |
| Break ; Tenacity | brittle |
| colour | black, dark reddish brown in transmitted light |
| Line color | dark reddish brown |
| transparency | translucent at thin corners, otherwise opaque |
| shine | weak metallic luster |
| Crystal optics | |
| Refractive indices |
n α = 1.730 n β = 1.960 n γ = 1.980 |
| Birefringence | δ = 0.250 |
| Optical character | biaxial negative |
| Pleochroism | Visible: X = light reddish brown Y ^ c 15 ° = deep reddish brown Z = b = dark reddish brown |
Melanovanadit is a rarely occurring mineral from the mineral class of " oxides and hydroxides " with the chemical composition Ca [V +4 2 | V 5+ 2 O 10 ] · 5H 2 O, making it a hydrous calcium - vanadate , crystal-chemically with the Oxides / hydroxides is related.
Melanovanadite crystallizes in the triclinic crystal system and develops up to two millimeters long prismatic according to the c-axis [001] stretched and striped crystals in star-shaped or rosette-like aggregates . The mineral is generally black and opaque, but shows a translucent dark reddish brown color on thin edges. The surfaces of the crystals have a faint metallic sheen .
Etymology and history
The mineral was first discovered in 1920 by the engineer WS Hutchinson, who worked for the Vanadium Company, in Minas Ragra near Cerro de Pasco in Peru . He handed the three discovered mineral samples over to Waldemar Lindgren for analysis, who was able to confirm that this was a previously unknown mineral.
Lindgren named the mineral melanovanadite based on its black color ( Greek μέλας mélas "black") and the element vanadium contained in the chemical formula and published his results in 1921 in the Proceedings of the National Academy of Sciences .
Type material of the mineral is available from Harvard University in Cambridge , Massachusetts under catalog no. 90452, in the American Museum of Natural History in New York City under catalog no. 19310 and in the National Museum of Natural History in Washington, DC under catalog no. Retained in USA 138067 and 160076.
classification
Already in the outdated, but still in use 8th edition of the mineral classification according to Strunz , the melanovanadite belonged to the mineral class of "oxides and hydroxides" and there to the department of "vanadium oxides (polyvanadates with V 4+ / 5+ )", of which it was the only member formed the unnamed group IV / G.10 .
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 melanovanadite in the "V [5,6] -Vanadate" division. This is, however, further subdivided according to the structure of the vanadate complexes, so that the mineral can be found according to its structure in the sub-section "Layered vanadates (Phyllovanadates)", where it is the only member of the unnamed group 4.HE.05 .
The predominantly common in the English language nomenclature of minerals by Dana contrast, assigns the Melanovanadit in the class of "phosphates, arsenates and vanadates" and then in the Department of " Vanadium - oxy-salts " one. Here he is to be found as the only member of the unnamed group 47.03.06 within the subdivision "Vanadium oxy salts (water-containing)".
Crystal structure
Melanovanadite crystallizes trikine in space group P 1 (space group no. 2) with the lattice parameters a = 6.36 Ångström , b = 18.09 Å, c = 6.28 Å, α = 110.18 °, β = 101, 62 ° and γ = 82.86 ° as well as two formula units per unit cell .
Within the structure there is a substructure which corresponds to the chemical formula CaV 4 O 10 · 5 H 2 O and has a layer structure.
The water contained in the mineral is gradually released when heated. From 200 to 250 ° C, all the water has escaped from the crystal and the mineral appears amorphous in X-ray diffraction .
properties
Melanovanadit is easily soluble in nitric acid (HNO 3 ), hydrochloric acid (HCl) and dilute sulfuric acid (H 2 SO 4 ), whereby the solution turns green.
Education and Locations
Melanovanadite formed as a secondary mineral in vanadium-rich aged shale rocks or, in the Colorado finds, in uranium- vanadium deposits. As Begleitminerale here were gypsum , copper , Pascoite , patronite , pyrite and Sherwoodit on.
As a rare mineral formation, melanovanadite could only be detected in a few places, although around 20 sites are known to date (as of 2017). Its type locality Minas Ragra is the only known site in Peru to date.
Other previously known sites are the "Mounana Mine" near Franceville in Gabon , Prachovice in the Pardubice region (Bohemia) in the Czech Republic and some mines in the Lukachukai Mountains in Apache County of Arizona, the "Garfield Mine" in the county of the same name and several mines in Montrose County of Colorado and some mines in Grand Counties and San Juan Counties of Utah.
See also
literature
- Waldemar Lindgren : Melanovanadite, a new mineral from Mina Ragra, Pasco, Peru . In: Proceedings of the National Academy of Sciences . tape 7 , 1921, pp. 249–251 ( rruff.info [PDF; 111 kB ; accessed on March 5, 2017]).
- ET Wherry: New minerals: new species . In: American Mineralogist . tape 7 , 1922, pp. 162-164 .
- Judith A. Konnert, Howard T. Evans, Jr .: Crystal structure and crystal chemistry of melanovanadite, a natural vanadium bronze . In: American Mineralogist . tape 72 , 1987, pp. 637–644 ( rruff.info [PDF; 880 kB ; accessed on March 5, 2017]).
Web links
- Mineral Atlas: Melanovanadite
- RRUFF Database-of-Raman-spectroscopy - Melanovanadite (English)
- American-Mineralogist-Crystal-Structure-Database - Melanovanadite (English)
Individual evidence
- ↑ a b c d Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables. Chemical-structural Mineral Classification System . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 259 .
- ^ IMA / CNMNC List of Mineral Names; January 2017 (PDF 1.66 MB)
- ↑ Webmineral - Melanovanadite (English)
- ↑ a b c d e f Melanovanadite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 69 kB ; accessed on March 5, 2017]).
- ↑ a b c d Mindat Mindat - Melanovanadite (English)
- ^ Waldemar Lindgren : Melanovanadite, a new mineral from Mina Ragra, Pasco, Peru . In: Proceedings of the National Academy of Sciences . tape 7 , 1921, pp. 251 ( rruff.info [PDF; 111 kB ; accessed on March 5, 2017]).
- ↑ Mindat - Number of localities for Melanovanadite
- ↑ Find location list for melanovanadite at the Mineralienatlas and at Mindat