Palenzonaite
| Palenzonaite | |
|---|---|
 |
|
| General and classification | |
| other names |
IMA1986-011 |
| chemical formula | Ca 2+ 2 Na + Mn 2+ 2 V 5+ 3 O 12 |
|
Mineral class (and possibly department) |
Phosphates, arsenates and vanadates |
|
System no. to Strunz and to Dana |
8.AC.25 ( 8th edition : 7 / A.08-50) 38.2.1.3 |
| Crystallographic Data | |
| Crystal system | cubic |
| Crystal class ; symbol | cubic hexakisoctahedral; 4 / m 3 2 / m |
| Space group | Ia 3 d (No. 230) |
| Lattice parameters |
a = 12.573 (synthetic end link ) 12.543 (natural mixed crystal) Å |
| Formula units | Z = 8 |
| Physical Properties | |
| Mohs hardness | 5 to 5.5 |
| Density (g / cm 3 ) | natural mixed crystal: 3.69 (measured), 3.77 (calculated) |
| Cleavage | not observed |
| Break ; Tenacity | shell-like |
| colour | wine red |
| Line color | brown-red |
| transparency | Please complete |
| shine | Diamond luster |
| Crystal optics | |
| Refractive index | n = 1.965 (natural mixed crystal) |
| Birefringence | isotropic |
The mineral palenzonaite is a very rare vanadate from the garnet group and has the idealized chemical composition Ca 2+ 2 Na + Mn 2+ 2 V 5+ 3 O 12 . It crystallizes in the cubic crystal system with the structure of garnet.
Palenzonaite occurs in the form of wine-red, diamond-shining crystals up to 6 millimeters in size. The crystal form is dominated by the rhombic dodecahedron {110}.
Palenzonait is formed in the metamorphosis of manganese deposits. The type locality is the Molinello mine, known for its rare manganese minerals, in the Graveglia valley in the Ligurian Apennines near Ne in the metropolitan city of Genoa , Liguria , Italy .
Etymology and history
Palenzonaite was described in 1987 by Riccardo Basso, after whom the mineral bassoite was named. Basso named the new mineral of the Berzeliite group after the amateur mineralogist and professor of chemistry at the University of Genoa , Andrea Palenzona, who discovered it in the Molinello manganese mine in Liguria.
classification
The current classification of the International Mineralogical Association (IMA) counts the palenzonaite to the garnet upper group, where together with berzeliite , manganese berzeliite and schäferite it forms the berzeliite group with 15 positive charges on the tetrahedral coordinated lattice position.
In the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the palenzonaite belongs to the mineral class of "phosphates, arsenates and vanadates" and there to the department of "anhydrous phosphates [PO 4 ] 3− , without foreign anions", where it together with Berzeliit , Chladniit , Fillowit , Galileiit , Johnsomervilleit , Manganberzeliit , Schäferit , Storneseit- (Y) and Xenophyllit the unnamed group VII / A.08 forms.
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 assigns the palenzonaite to the category of “phosphates etc. without additional anions; without H 2 O “. However, this is further subdivided according to the relative size of the cations involved , so that the mineral can be found according to its composition in subsection C "With medium-sized and large cations", where berzeliite , manganese berzelite and schäferite belong to the berzeliite group 8.AC.25 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the palenzonaite to the class of "phosphates, arsenates and vanadates" and there in the department of "anhydrous phosphates etc.". Here it is together with berzeliite, manganese berzelite and schäferite in the Berzeleiite group systematics of minerals according to Dana / Phosphate, Arsenate, Vanadate # 38.02.01 Berzeliite group within the subdivision “38.02 Anhydrous phosphates etc., (A + B 2+ ) 5 (XO 4 ) 3 ”.
Chemism
Palenzonait with the idealized composition [X] (Na + Ca 2+ 2 ) [Y] Mn 2+ 2 [Z] V 5+ 3 O 12 is the manganese -Analog of Schäferit ( [X] (Na + Ca 2+ 2 ) [Y] Mg 2+ 2 [Z] V 5+ 3 O 12 ) or the vanadium analogue of berzeliite ( [X] (Na + Ca 2+ 2 ) [Y] Mg 2+ 2 [Z] As 5 + 3 O 12 ).
The following compositions are given for Palenzonaite from the type locality: - [X] (Ca 2+ 2.374 Na + 0.616 ) [Y] Mn 2+ 1.994 [Z] (V 5+ 2.430 As 5+ 0.251 Si 4+ 0.310 ) O 12 - [X] (Ca 2+ 2.25 Na + 0.78 ) [Y] (Mn 2+ 1.84 Ni 2+ 0.01 V 3+ 0.11 ) [Z] (V 5+ 2.64 As 5+ 0.17 Si 4+ 0.19 ) O 12
There is at least a partial miscibility with Berzeliite according to the exchange reaction - [Z] V 5+ = [Z] As 5+
The calcium content in the X position can be well above the maximum value to be expected for grenades in this group. The charge equalization takes place by incorporating Si on the tetrahedral position corresponding to an exchange reaction - [X] Na + + [Z] V 5+ = [X] Ca 2+ + [Z] Si 4+
The composition given by Nagashima and Armbruster can be interpreted as mixed crystal formation with goldmanite : - [Y] Mn 2+ + [Z] V 5+ = [Y] V 3+ + [Z] Si 4+
Crystal structure
Palenzonaite crystallizes with cubic symmetry in the space group Ia 3 d (space group no. 230) with 8 formula units per unit cell . The natural mixed crystal from the type locality has the lattice parameter a = 12.543 Å . The lattice parameter of synthetic, pure palenzonaite is somewhat larger: a = 12.573 Å.
The structure is that of garnet . Sodium (Na + ) and calcium (Ca 2+ ) occupy the dodecahedral X position surrounded by 8 oxygen ions, manganese (Mn 2+ ) the octahedral Y position surrounded by 6 oxygen ions and the tetrahedral Z position surrounded by 4 oxygen ions is exclusive occupied with vanadium (V 5+ ).
Education and Locations
Natural palenzonaite forms secondarily under oxidizing conditions with low-grade metamorphosis in manganese deposits.
The type locality is the Molinello manganese mine in the Graveglia Valley in the Ligurian Apennines near Ne in the metropolitan city of Genoa , Liguria , Italy . Palenzonaite occurs here in small corridors together with calcite , braunite , saneroite , ganophyllite and axinite . This manganese deposit is type locality numerous other, less common minerals, including Arsenmedait , Bassoite , Cortesognoite , Medaite , Molinelloite , Paseroite , Piemontite- (Sr) , Tiragalloite and Vanadiocarpholite .
Palenzonaite was also found in other manganese mines in the Graveglia valley. Other Italian deposits are in Piedmont in the province of Cuneo .
Outside Italy Palenzonait was still in Switzerland in Val Ferrera in Grisons found where he and Medait , Saneroite, Pyrobelonit , Fianelit , Parsettensite , rhodochrosite , Kutnohorit , Aegirin and quartz occurs.
Outside of Europe, palenzonaite has been documented in the Yamato Mine on Amami-Ōshima Island in Kagoshima Prefecture , Kyūshū , Japan .
See also
Web links
- Mineral Atlas: Palenzonaite (Wiki)
- Mindat - Palenzonait (English)
Individual evidence
- ↑ a b c d e f g h i j k l m n o p q John L. Jambor, Kenneth W. Bladh, T. Scott Ercit, Joel D. Grice, Edward S. Grew: New Mineral Names: Palenzonaite . In: American Mineralogist . tape 73 , 1988, pp. 927-935 ( rruff.info [PDF; 900 kB ; accessed on March 23, 2018]).
- ↑ a b c d e f M. Nagashima, and T. Armbruster: Palenzonaite, berzeliite, and manganberzeliite: (As5 +, V5 +, Si4 +) O4 tetrahedra in garnet structures . In: Mineralogical Magazine . tape 76 , 2012, p. 1081-1097 ( rruff.info [PDF; 379 kB ; accessed on March 23, 2018]).
- ^ Edward S. Grew, Andrew J. Locock, Stuart J. Mills, Irina O. Galuskina, Evgeny V. Galuskin and Ulf Hålenius: IMA Report - Nomenclature of the garnet supergroup . In: American Mineralogist . tape 98 , 2013, p. 785–811 ( main.jp [PDF; 2,3 MB ; accessed on July 8, 2017]).
- ↑ a b JW Anthony, RA Bideaux, KW Bladh and MC Nichols: Palenzonaite . In: Handbook of Mineralogy . 1990 ( rruff.info [PDF; 64 kB ; accessed on March 26, 2018]).
- ↑ a b c d List of localities for Palenzonaite in the Mineralienatlas and Mindat