Phoenicochroit
| Phoenicochroit | |
|---|---|
 |
|
| General and classification | |
| other names |
|
| chemical formula | Pb 2 [O | CrO 4 ] |
|
Mineral class (and possibly department) |
Sulfates (including selenates, tellurates, chromates, molybdates, and tungstates) |
|
System no. to Strunz and to Dana |
7.FB.05 ( 8th edition : VI / F.02) 01/35/02/01 |
| Similar minerals | Crocoite , realgar |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Room group (no.) | C 2 / m (No. 12) |
| Lattice parameters |
a = 14.00 Å ; b = 5.68 Å; c = 7.14 Å β = 115.2 ° |
| Formula units | Z = 4 |
| Frequent crystal faces | {010}, {100}, {110}, { 2 01}, { 2 11}, {310} |
| Physical Properties | |
| Mohs hardness | 2.5 to 3.5 |
| Density (g / cm 3 ) | measured: 7.01; calculated: 7.075 |
| Cleavage | completely after { 2 01}, indistinct after {001}, {010}, {011} |
| colour | dark red (cochineal red to hyacinth red), turning yellow through weathering |
| Line color | brick red to yellowish orange |
| transparency | translucent, transparent on thin edges |
| shine | glittering resin to diamond shine |
| Crystal optics | |
| Refractive indices |
n α = 2.380 n β = 2.440 n γ = 2.650 |
| Birefringence | δ = 0.270 |
| Optical character | biaxial positive |
| Axis angle | 2V = 58 ° (measured); 62 ° (calculated) |
Phoenicochroite also phoenicochroite or Melanochroit is a naturally occurring mineral from the mineral class of "sulfates (including selenates, tellurates, chromates, molybdates and tungstates)". It crystallizes in the monoclinic crystal system with the chemical composition Pb 2 [O | CrO 4 ], so it is chemically seen a lead - chromate with additional oxygen ions and therefore under its chemical name chrome red known.
Phoenicochroit usually develops imperfect, tabular crystals up to about one centimeter in size and a resin-like to diamond-like sheen on the surfaces, but also occurs in the form of reticulated adhesions, thin crusts or massive aggregates . The crystals are generally translucent with only thin edges transparent. Fresh samples are dark red in color, but gradually turn yellow with weathering. Phoenicochroit leaves a brick-red to yellowish- orange line on the marking board .
With a Mohs hardness of 2.5 to 3.5, Phoenicochroit is one of the soft to medium-hard minerals and is either slightly easier or more difficult to scratch with a copper coin than the reference mineral calcite (3).
Etymology and history
The mineral was first discovered and described in 1833 by R. Hermann, who noticed a few specimens in his collection "Red lead ores" ( crocoite ) from Berezovsk (today Berjosowski (Sverdlovsk) , Russia) whose external properties differed greatly from those of the well-known red lead ore . He described the color of the previously unknown mineral as cochineal red to hyacinth red , which changes into bitter orange yellow through weathering . According to Hermann, it was particularly noticeable that the mineral, in contrast to crocoite, did not decrepit (cracked and crackled). In order to emphasize the darker color in contrast to the crocoite, Hermann called the new mineral melanochroit after the ancient Greek words μελανός [melanos] for "dark" or "black" and χρώς [chrōs] for "color".
The name Phönikochroit, which is still valid today, was given to the mineral in 1839 by Ernst Friedrich Glocker , who considered the name chosen by Hermann to be indicative, but also misleading due to the wrong choice of words. Glocker therefore also referred to the striking deep red color, but more precisely named it after the ancient Greek word φοίνικος [phoínikos] for "purple red".
A mineral described by Arno Mücke in 1970, which he called Scheibeit (after Robert Scheibe, 1859–1923, Professor of Mineralogy at the Technical University of Berlin ), turned out to be identical to Phönikochroit in subsequent investigations. A mineral described as chrominium in 1972 is also identical to Phoenicochroit. Both mineral names were therefore discredited in 1980 by the International Mineralogical Association (IMA) and have since been considered synonyms for the Phoenicochroit.
classification
In the 8th edition of the mineral systematics according to Strunz , which is out of date, but still in use , the phenicochroit belonged to the mineral class of "sulfates, chromates, molybdates, wolframates" and there to the "chromates" department, where together with vauquelinite it was the "Phoenicochroit vauquelinite" Group "with the system no. VI / F.02 and the other members deaesmithite , edoylerite , fornacite , molybdofornacite , santanaite and wattersite .
The 9th edition of Strunz's mineral systematics, which has been in force since 2001 and is used by the IMA, also classifies Phoenicochroit into the “chromates” division. However, this is further subdivided according to the possible presence of additional anions, so that the mineral can be found according to its composition in the sub-section "With additional O, V, S, Cl", where it is the only member of the unnamed group 7.FB.05 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Phoenicochroit to the class of "sulfates, chromates and molybdates" and there in the department of "anhydrous chromates". Here he is the only member of the unnamed group 01/35/02 within the sub-section “ Anhydrous chromates with (A + ) 2 XO 4 ”.
Education and Locations
Phenicochroite forms secondarily in the oxidation zone of chromium-containing, hydrothermal lead deposits . As accompanying minerals may include calcite , Cerussite , Fornacit , galena , Hemihedrit , Iranit , Krokoit , Leadhillit , Mimetite , Pyromorphite , Vauquelinite , fluorite , quartz .
As a rare mineral formation, Phoenicochroit could only be detected at a few sites, with around 35 sites known so far (as of 2014). Its type locality Berjosowski in the Sverdlovsk Oblast is the only known site in Russia to date.
In Germany, the mineral has so far only been found in the Callenberg opencast mine in Saxony and the only known site in Austria is the slag heaps of the Brixlegg coal and steel works in the Tyrolean municipality of the same name .
Other previously known sites include several locations in the Antofagasta region in Chile, Anarak in the Isfahan province and Nayband (Neyband) in the Yazd province in Iran, the Husab open-cast mine in the Namib-Naukluft Park in Namibia, Argent (Mpumalanga) in the South African province of Gauteng , Wanlock Dod in the Scottish county of Lanarkshire (UK) and several places in the US states of Arizona and Nevada .
Crystal structure
Phoenicochroit crystallizes isostructural with lanarkite in the monoclinic crystal system in the space group C 2 / m (space group no. 12) with the lattice parameters a = 14.00 Å ; b = 5.68 Å; c = 7.14 Å and β = 115.2 ° as well as four formula units per unit cell .
See also
literature
- R. Hermann: About the Melanochroit, a new mineral. In: Annals of Physics and Chemistry. Volume 28 (1833), pp. 162–164 ( PDF 190.9 kB )
- Ernst Friedrich Glocker : 19th Phoenicochroit. In: Grundriß der Mineralogie, including geognosy and Petrefactenkunde. Publisher by Johann Leonhard Schrag , Nuremberg 1839, pp. 612–612 ( PDF 191.3 kB )
Web links
- Mineral Atlas: Phoenicochroit (Wiki)
- Web mineral - Phoenicochroite
- Database-of-Raman-spectroscopy - Phoenicochroite
- American-Mineralogist-Crystal-Structure-Database - Phoenicochroite
Individual evidence
- ↑ a b c International Mineralogical Association: Commission on new minerals and mineral names. In: Mineralogical Magazine. 43: 1053-1055 (1980). ( PDF 171.9 kB ; name corrections and discredited mineral names)
- ↑ 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. 416 .
- ↑ a b Phoenicochroite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 65.5 kB )
- ↑ a b c Mindat - Phoenicochroite
- ↑ Hans Jürgen Rösler : Textbook of Mineralogy . 4th revised and expanded edition. German publishing house for basic industry (VEB), Leipzig 1987, ISBN 3-342-00288-3 , p. 684 .
- ↑ Arno Mücke : Scheibeite, a new chromate mineral. In: New Yearbook of Mineralogy. Monthly books. Volume 6 (1970), pp. 276-282; See also Michael Fleischer : New Mineral Names. In: American Mineralogist. Volume 56 (1971), pp. 358-362 ( PDF 334.6 kB ; Scheibeite = Phoenicochroite from p. 2)
- ↑ Mindat - Number of localities for Phoenicochroit (Phoenicochroite)
- ↑ Find location list for Phoenicochroit at the Mineralienatlas and at Mindat