Attikait
| Attikait | |
|---|---|
 |
|
| General and classification | |
| other names |
IMA 2006-017 |
| chemical formula | Ca 3 Cu 2 Al 2 (AsO 4 ) 4 (OH) 4 · 2H 2 O |
|
Mineral class (and possibly department) |
Phosphates, arsenates and vanadates |
|
System no. to Strunz and to Dana |
8.DJ.45 ( 8th edition : VII / D.25) 42.06.05.03 |
| Crystallographic Data | |
| Crystal system | orthorhombic |
| Crystal class ; symbol | orthorhombic dipyramidal or pyramidal; 2 / m 2 / m 2 / m or mm 2 |
| Room group (no.) | Pban , Pbam or Pba 2 (No. 50, 55 or 32) |
| Lattice parameters | a = 10.01 (1) Å ; b = 8.199 (5) Å; c = 22.78 (1) Å |
| Formula units | Z = 4 |
| Physical Properties | |
| Mohs hardness | 2 to 2.5 |
| Density (g / cm 3 ) | measured: 3.2 (2); calculated: 3.356 |
| Cleavage | completely after {001} |
| Break ; Tenacity | not defined; flexible |
| colour | light blue to greenish blue; colorless in transmitted light |
| Line color | very light blue |
| transparency | transparent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.642 (2) n β = 1.644 (2) n γ = 1.644 (2) |
| Birefringence | δ = 0.002 |
| Optical character | biaxial negative |
| Axis angle | 2V = 10 ° |
Attikaite is a very rare mineral from the mineral class of " phosphates , arsenates and vanadates ". It crystallizes in the orthorhombic crystal system with the chemical composition Ca 3 Cu 2 Al 2 (AsO 4 ) 4 (OH) 4 · 2H 2 O, so it is a water-containing calcium - copper - aluminum arsenate with additional hydroxide ions .
Attikait develops curved, scaly crystals with a glass-like sheen on the surfaces, which are usually connected to spherical mineral aggregates with a diameter of about 0.3 millimeters. Its color varies between light blue and greenish blue, but it appears colorless in transmitted light. His line color is a very light blue.
Etymology and history
Attikaite was first discovered in the "Christiana tunnel" (shaft no. 132) near Agios Konstantinos (municipality Lavrio ) in the Greek region of Attica and described in 2007 by NV Chukanov, IV Pekov and AE Zadov, who named the mineral after its type of locality .
classification
Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the attikaite belonged to the mineral class of "phosphates, arsenates and vanadates" and there to the department of "water-containing phosphates with foreign anions ", where together with andyrobertsite , birchite , Calcio-Andyrobertsit , Englishit , Esperanzait , Goldquarryit , Lavendulan , Lemanskiit , Mahnertit , Sampleit , Shubnikovit and Zdenĕkit the "Lavendulan Group" with the system no. VII / D.25 formed.
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 Attikaite to the category of “Phosphates etc. with additional anions; with 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 can be classified in the sub-section “With large and medium-sized cations; (OH etc.): RO 4 = 1: 1 “can be found where it is the only member of the unnamed group 8.DJ.45 .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Attikaite to the class of "phosphates, arsenates and vanadates" and there to the category of "water-containing phosphates, etc., with hydroxyl or halogen". Here he is together with arhbarite and strashimirite in the " strashimirite group " with the system no. 42.06.05 within the subsection “Water-containing phosphates etc., with hydroxyl or halogen with (AB) 2 (XO 4 ) Z q × x (H 2 O)”.
Education and Locations
Attikait forms as a secondary mineral in the oxidized zones of polymetallic sulphide - quartz - veins , where he next quartz, among others, still with allophane , Arsenocrandallit , Arsenogoyazit , azurite and malachite , Beudantit , Conichalcite , goethite , Karminit , Olivenit and Philipsbornite socialized occurs.
In addition to its type locality “Christiana-Stollen” in the Greek region of Attica, only the “La Amorosa” mine in the municipality of Villahermosa del Rio in the Spanish province of Castellón is known to be the site of Attikaite (as of 2013).
Crystal structure
Attikaite crystallizes orthorhombically in the space group Pban , Pbam or Pba 2 (space group no. 50, 55 or 32) with the lattice parameters a = 10.01 (1) Å ; b = 8.199 (5) Å and c = 22.78 (1) Å as well as four formula units per unit cell .
See also
literature
- NV Chukanov, IV Pekov, AE Zadov: Attikaite, Ca 3 Cu 2 Al 2 (AsO 4 ) 4 (OH) 4 · 2H 2 O, a new mineral species. In: Geology of Ore Deposits. Volume 49 (2007), pp. 720–726 ( PDF 307.2 kB )
Web links
Individual evidence
- ↑ a b c d e NV Chukanov, IV Pekov, AE Zadov: Attikaite, Ca 3 Cu 2 Al 2 (AsO 4 ) 4 (OH) 4 2H 2 O, a new mineral species. In: Geology of Ore Deposits. Volume 49 (2007), pp. 720–726 ( PDF 307.2 kB )
- ↑ a b c Attikaite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF kB )
- ↑ a b c Mindat - Attikaite
- ↑ Find location list for Attikait at the Mineralienatlas and at Mindat