Aldermanite
| Aldermanite | |
|---|---|
 |
|
| General and classification | |
| other names |
IMA 1980-044 |
| chemical formula | Mg 5 Al 12 [(OH) 22 | (PO 4 ) 8 ] • 32H 2 O |
|
Mineral class (and possibly department) |
Phosphates, arsenates and vanadates |
|
System no. to Strunz and to Dana |
8.DE.35 ( 8th edition : VII / D.17) 42.13.01.01 |
| Crystallographic Data | |
| Crystal system | orthorhombic |
| Crystal class ; symbol | not defined |
| Lattice parameters | a = 15.00 Å ; b = 8.33 Å; c = 26.00 Å |
| Formula units | Z = 2 |
| Physical Properties | |
| Mohs hardness | 2 |
| Density (g / cm 3 ) | calculated: 2.0 to 2.15 |
| Cleavage | Please complete |
| colour | colorless to white |
| Line color | White |
| transparency | transparent to translucent |
| shine | Pearl luster, faint glass luster |
| Crystal optics | |
| Refractive index | n = 1,500 |
| Birefringence | δ = 0.000 |
| Optical character | biaxial |
Aldermanite is a very rarely occurring mineral from the mineral class of " phosphates , arsenates and vanadates ". It crystallizes in the orthorhombic crystal system with the composition Mg 5 Al 12 [(OH) 22 | (PO 4 ) 8 ] · 32H 2 O, so it is chemically a water-containing magnesium - aluminum phosphate with hydroxide as additional anions .
Aldermanite is mostly found in the form of fibrous or flake-like mineral aggregates , which have a certain similarity to talc . However, it rarely develops thin-tabular to prismatic, radial-rayed crystals of a few millimeters in size. In its pure form, aldermanite is colorless and transparent. However, due to multiple light refraction due to lattice construction defects or polycrystalline formation, it can also appear white, with the transparency decreasing accordingly.
Etymology and history
Aldermanite was first discovered in the Moculta phosphate quarry near Angaston in the Barossa Valley of South Australia and described in 1981 by Ian R. Harrowfield, Edgar Ralph Segnit and John. A. Watts, who named the mineral after Arthur Richard Alderman (1901–1980).
classification
Aldermanite belonged to the mineral class of "phosphates, arsenates and vanadates" and there to the department of "water-containing phosphates with foreign anions ", where it was the only member of the unnamed group, in the 8th edition of the mineral classification according to Strunz , which is now outdated but still in use VII / D.17 formed.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 aldermanite to the class of “phosphates, arsenates and vanadates” and there to the department of “phosphates etc. with additional anions ; with H 2 O “. However, this section is further subdivided according to the relative size of the cations involved and the molar ratio of the other anions (OH etc.) to the phosphate, arsenate or vanadate complex (RO 4 ), so that the mineral can be classified in the sub-section " With only medium-sized cations; (OH etc.): RO 4 = 3: 1 “can be found where it is the only member of the unnamed group 8.DE.35 .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns aldermanite 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 to be found as the only member in the unnamed group 42.13.01 within the subdivision of " Water-containing phosphates etc., with hydroxyl or halogen ".
Crystal structure
Aldermanite crystallizes orthorhombically, although the exact space group has not yet been determined. The lattice parameters are a = 15.00 Å ; b = 8.33 Å and c = 26.00 Å with 2 formula units per unit cell .
Education and Locations
Aldermanite is secondary to the weathering of fluellite in the cavities of breccias in sedimentary phosphate deposits .
In addition to its type locality Moculta phosphate quarry, the mineral has so far (as of 2012) been detected in the Penrice marble quarry, also located near Angaston, and at Tom's phosphate quarry near Kapunda in the Barossa Valley of South Australia.
See also
literature
- IR Harrowfield, ER Segnit, JA Watts: Aldermanite, a new magnesium aluminum phosphate . In: Mineralogical Magazine . tape 44 , 1981, pp. 59–62 ( rruff.info [PDF; 377 kB ; accessed on March 29, 2018]).
Web links
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. 505 .
- ^ Aldermanite . 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; 63 kB ; accessed on March 29, 2018]).
- ↑ a b c Mindat - Aldermanite