Hermannroseit

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Hermannroseit
General and classification
other names

IMA 2010-0006

chemical formula CaCu (PO 4 , AsO 4 ) (OH)
Mineral class
(and possibly department) 		Phosphates, arsenates, vanadates
System no. to Strunz
and to Dana 		8.BH.35 ( 8th edition : VII / B.26) 05.41.01.11
(?)
Crystallographic Data
Crystal system orthorhombic
Crystal class ; symbol orthorhombic-disphenoidic; 222
Space group P 2 1 2 1 2 1 (No. 19)Template: room group / 19
Lattice parameters a  = 7.328  Å ; b  = 9.123 Å; c  = 5.769 Å
Formula units Z  = 4
Physical Properties
Mohs hardness not definable
Density (g / cm 3 ) 4.08 (calculated)
Cleavage not specified
Break ; Tenacity not specified; not specified
colour grass green
Line color pale green
transparency translucent to translucent
shine Glass gloss
Crystal optics
Refractive index n  = 1.77 (calculated)
Optical character biaxial, orientation cannot be determined
Pleochroism probably strong from yellow-green through emerald green to blue-green as in Konichalcite

Hermannroseit is an extremely rare mineral from the mineral class of " phosphates , arsenates and vanadates ". It crystallizes in the orthorhombic crystal system with the chemical composition CaCu (PO 4 , AsO 4 ) (OH) and is therefore chemically a calcium - copper - phosphate - arsenate with an additional hydroxide ion .

Hermannroseit can be found at its type locality in the form of up to 3 mm thick, kidney-shaped aggregates and crusts, which consist of konichalcite with enclosed alternating sequences of microcrystalline konichalcite, Hermannroseit, hydroxyapatite and whitlockite . The mean grain size of the Hermannro side is 0.7 μm.

The type locality of the mineral is the so-called second oxidation zone (28th level, mining location East 49) of the Tsumeb Mine near Tsumeb , Oshikoto region , Namibia .

Etymology and history

Hermannroseit was discovered on a mineral scale that the former pit geologist of the Tsumeb Mine and chief mineralogist of the Tsumeb Corporation Limited Bruno Herrmann Geier (1902–1987) had collected in the 1960s in the second oxidation zone of the Tsumeb Mine. Geier's heirs made this mineral available to the authors of the type publication for identification. Corresponding investigations led to the determination of the presence of a new mineral, which was recognized in May 2010 by the International Mineralogical Association (IMA) under the provisional designation IMA 2011-053. A German research team with Jochen Schlueter , Dieter Pohl and Georg Gebhard carried out the first scientific description of this mineral as Hermannroseit ( English Hermannroseite ) in the German science magazine “New Yearbook for Mineralogy, Treatises” in 2011 . The authors named the mineral after the German mineralogist, crystallographer and university professor Hermann Rose (1883-1976), former head of the Mineralogical-Petrographic Institute of the University of Hamburg and since 1972 honorary member of the German Mineralogical Society .

Type material of the mineral is kept in the Mineralogical Museum of the University of Hamburg in Germany (holotype, collection no. MMHH TS 637, in the safe of the museum).

classification

The 8th edition of the mineral classification according to Strunz , which is out of date but still in use in some cases, does not yet list the Hermannroseit. It would probably belong to the mineral class of "phosphates, arsenates and vanadates" and to the department of "anhydrous phosphates with foreign anions ", where together with adelite , austinite , cobaltaustinite , smellite , gabrielsonite , gottlobite , konichalcite , nickelustinite and tangeit the " Adelitgruppe “with the system no. VII / B.26 .

The 9th edition of Strunz's mineral systematics, which has been valid since 2001 and is used by the IMA, also does not yet know the Hermannroseit. Here he would also be in the department of "Phosphates, Arsenate and Vanadates" and there in the department of "Phosphates, etc. with additional anions; without H 2 O “. However, this is further subdivided according to the relative size of the cations involved and the molar ratio of the additional anions (OH, etc.) to the phosphate, arsenate or vanadate complex RO 4 , so that the mineral is classified according to its composition in the subsection “With medium-sized and mostly large cations; (OH etc.): RO 4  = 1: 1 ”is to be found, where together with Adelite, Arsendescloizit , Austinite, Cobaltaustinite, Duftite, Gabrielsonite, Gottlobit, Konichalcite, Nickelaustinite and Tangeit the“ Adelite Group ”with the system no. 8.BH.35 forms.

Also the systematics of minerals according to Dana , which is mainly used in the English-speaking world , would place Hermannroseit in the class of "phosphates, arsenates and vanadates" and there in the department of "anhydrous phosphates, etc., with hydroxyl or halogen". Here it would also be together with Adelite, Austinite, Duftit-Beta , Gabrielsonite, Tangeit, Konichalcite, Nickelaustinite, Cobaltaustinite, Arsendescloizit and Gottlobit in the "Adelite group" with the system no. 41.05.01 to be found within the subsection of " Anhydrous phosphates etc., with hydroxyl or halogen with (AB) 2 (XO 4 ) Z q ".

Chemism

One hundred and fifty microprobe analyzes on Hermannroseit from the "Tsumeb Mine" resulted in mean values ​​of 22.80% CaO; 34.52% CuO; 0.58% ZnO; 15.16% P 2 O 5 ; 21.88% As 2 O 5 ; 1.02% V 2 O 5 ; 4.04% H 2 O (calculated from the difference), from which, based on five oxygen atoms pfu (per formula unit), the empirical formula Ca 0.96 (Cu 1.03 Zn 0.02 ) (P 0.51 As 0.45 V 0.03 ) O 3.94 (OH) 1.06 . For the analysis with the highest phosphorus content, the empirical formula was calculated as Ca 0.96 (Cu 0.99 Zn 0.01 ) (P 0.64 As 0.30 V 0.01 ) O 3.68 (OH) 1, 32 . The empirical formula can be idealized to CaCu (PO 4 , AsO 4 ) (OH), whereby the formula for the pure phosphate end link is given as CaCuPO 4 (OH).

Hermannroseit is the phosphate-dominant analogue of the arsenate-dominated konichalcite. Continuous substitution of P 5+ for As 5+ leads to the first phosphate mineral of the Adelite group as a subgroup of the Adelite-Descloizit group. Hermannroseit is also the phosphate-dominant analogue of the vanadate-dominated Tangeits, CaCuVO 4 (OH).

Crystal structure

Hermannroseit crystallizes in the orthorhombic crystal system in the space group P 2 1 2 1 2 1 (space group no. 19) with the lattice parameters a  = 7.328  Å ; b  = 9.123 Å and c  = 5.769 Å as well as four formula units per unit cell . Template: room group / 19

Hermannroseit is isotypic (isostructural) with its phosphate analogue konichalcite.

properties

morphology

Hermannroseit forms up to 3 mm thick, kidney-shaped mineral aggregates and crusts at its type locality , which consist of konichalcite with enclosed alternating sequences of microcrystalline konichalcite, Hermannroseit, hydroxyapatite and whitlockite . In these aggregates, Hermannroseit is found under a thin outer crust of Konichalcite. The mean grain size of the Hermannro side is 0.7 μm.

physical and chemical properties

Hermannroseit is grass green, but its line color is always pale green. The surfaces of the translucent to transparent aggregates have a glass-like sheen , which agrees well with the value for the mean refraction . According to calculations, this value is 1.77. Although no pleochroism was found on the thin sections of the Hermannroseit , Hermannroseit, analogous to Konichalcite, should have a strong pleochroism from yellow-green to emerald green to blue-green.

Neither cleavage nor breakage could be determined on the aggregates on the Hermannro side . There is also no information on tenacity. Due to the small grain size, the Mohs hardness could not be determined either. The density calculated from the unit cell and the empirical formula for Hermannroseit is 4.08 g / cm³. The mineral is neither in the long term nor in the short wavelength UV light , a fluorescent .

Education and Locations

As an extremely rare mineral formation (only a single stage is known) Hermannroseit could only be described from one site so far (status 2018). The type locality is the "Tsumeb Mine" near Tsumeb, Oshikoto region , Namibia , with the exact location within the mine on the 28th level, mining location East 49 in the area of ​​the second oxidation zone. There are no known occurrences of Hermannroseit in Germany , Austria or Switzerland .

Hermannroseit is a typical secondary mineral , which in the oxidation zone an arsenic-rich polymetallic non-ferrous metal - deposit has formed. Hermannroseit and Konichalcit were found here in the form of kidney-grape-like aggregates lining a druse in massive hydroxyapatite, which is colored black by amorphous manganese oxides and manganese hydroxides. Other paragenesis minerals are pseudomalachite and whitlockite.

use

With an average CuO content of 34.52% by weight, Hermannroseit would be copper ore . Due to its extreme rarity, it is only of interest to mineral collectors.

See also

literature

  • Jochen Schlüter, Dieter Pohl, Georg Gebhard: The new mineral hermannroseite, CaCu (PO 4 , AsO 4 ) (OH), the phosphate analogue of conichalcite, from Tsumeb, Namibia . In: New Yearbook for Mineralogy, Treatises . tape 188 , no. 2 , 2011, p. 135-140 , doi : 10.1127 / 0077-7757 / 2011/0186 .

Web links

Individual evidence

  1. ↑ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak Jochen Schlüter, Dieter Pohl, Georg Gebhard: The new mineral hermannroseite, CaCu (PO4, AsO4) (OH), the phosphate analogue of conichalcite, from Tsumeb, Namibia . In: New Yearbook for Mineralogy, Treatises . tape 188 , no. 2 , 2011, p. 135-140 , doi : 10.1127 / 0077-7757 / 2011/0186 .
  2. ^ Type mineral catalog Germany - storage of the holotype stage Hermannroseit
  3. ↑ Mindat - Hermannroseite (English)
  4. ↑ Mindat - Number of localities for Hermannroseit (English)
  5. ↑ a b List of locations for Hermannroseit in the Mineralienatlas and Mindat
  6. ↑ Tsumeb.com - Hermannrosite (English)