Petterdit
| Petterdit | |
|---|---|
 |
|
| General and classification | |
| other names |
IMA 1999-034 |
| chemical formula | Pb (Cr, Al) 2 [(OH) 2 | CO 3 ] 2 · H 2 O |
|
Mineral class (and possibly department) |
Carbonates and nitrates (formerly carbonates, nitrates and borates) |
|
System no. to Strunz and to Dana |
5.DB.10 ( 8th edition : V / E.08) 16b.02.01.04 |
| Crystallographic Data | |
| Crystal system | orthorhombic |
| Crystal class ; symbol | orthorhombic-dipyramidal; 2 / m 2 / m 2 / m |
| Space group | Pbnm (No. 62, position 3) |
| Lattice parameters | a = 9.079 Å ; b = 16.321 Å; c = 5.786 Å |
| Formula units | Z = 4 |
| Physical Properties | |
| Mohs hardness | 2 |
| Density (g / cm 3 ) | calculated: 3.947 |
| Cleavage | clearly after {100} |
| colour | violet |
| Line color | light purple |
| transparency | translucent |
| shine | Pearlescent to earthy matt |
| Crystal optics | |
| Refractive indices |
n α = 1.704 n β = 1.802 n γ = 1.842 |
| Birefringence | δ = 0.138 |
| Optical character | biaxial negative |
Petterdit is a very rarely occurring mineral from the mineral class of " carbonates and relatives" (see classification ). It crystallizes in the orthorhombic crystal system with the chemical composition Pb (Cr, Al) 2 [(OH) 2 | CO 3 ] 2 · H 2 O and thus represents the chromium analog of the dundasite (PbAl 2 [(OH) 2 | CO 3) ] 2 · H 2 O).
Petterdit only develops microscopic, tabular crystals up to about 15 μm in size or kidney, earthy mineral aggregates and crusty coatings of purple color and light purple line color .
Etymology and history
Petterdit was first found in 1999 in the "Red Lead Mine" near Dundas (Zeehan District) in Tasmania and described by William D. Birch, Uwe Kolitsch, Thomas Witzke , Lutz Nasdala and Ralph S. Bottrill, who named the mineral in honor of William Frederick Petterd (1849-1910), an amateur collector and publicist of numerous important lists on the mineralogy of Tasmania, named after him.
Petterdit was recognized as an independent mineral by the International Mineralogical Association (IMA) in the same year under the provisional designation IMA1999-034 . A year later, the test results and the recognized name Petterdit were published in The Canadian Mineralogist Vol. 38, pp. Published 1467-1476 (2000) .
classification
In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the Petterdit still belonged to the common mineral class of "carbonates, nitrates and borates " and there to the department of "water-containing carbonates with foreign anions", where it together with ankylite (La) , Ankylit- (Ce) , barstowite , Calcio-Ankylit- (Ce) , Calcio-Ankylit- (Nd) , Dresserit , Dundasit, Gysinit- (Nd) , Hydrodresserit , Kamphaugit- (Y) , Kochsándorit , Montroyalit , Strontiodresserit and Thomasclarkit- (Y) form a separate group.
Since the complete revision of Strunz's mineral systematics in the 9th edition (2001), the mineral class of carbonates (and relatives) has been redistributed and the borates form a class of their own. The Petterdit is therefore now in the mineral class of "carbonates and nitrates" and there in the department of "carbonates with additional anions; with H 2 O ”. However, this is now more precisely subdivided according to the size of the cations involved and the mineral is sorted according to its composition in the sub-section “With large and medium-sized cations”. There it belongs together with the eponymous Dresserite and the other members Dundasite, Kochsándorite, Montroyalite and Strontiodresserite to the Dresserite group with the system no. 5.DB.10 .
In the Dana system of minerals used in the English-speaking world , the carbonates, nitrates and borates form a common mineral class as in the outdated Strunz system. The Petterdit is there in the section of “ Carbonates with hydroxyl or halogen and the general formula (A) m (B) n (XO 3 ) p Z q • (H 2 O), with (m + n): p = 3: 2 ”, where it forms the unnamed group 16b.2.1 together with dundasite, dresserite, strontiodresserite and kochsundorite .
Crystal structure
Petterdit crystallizes orthorhombically in the space group Pbnm (space group no. 62, position 3) with the lattice parameters a = 9.079 Å ; b = 16.321 Å and c = 5.786 Å as well as 4 formula units per unit cell .
Education and Locations
Petterdite is formed as a rare secondary mineral by converting galena in chromium-containing, meteoritic waters or in the oxidation zone of hydrothermal veins into serpentinite . Accompanying minerals include angelsite , bindheimite , cerussite , galena, crocoite and pyromorphite .
Worldwide, Petterdit could so far (status: 2010) except for its type locality "Red Lead Mine" in Tasmania only in the Saxon town of Callenberg in Germany.
See also
literature
- William D. Birch, Uwe Kolitsch, Thomas Witzke, Ralph S. Bottrill: Petterdite, the Cr-dominant analogue of dundasite, a new mineral species from Dundas, Tasmania, Australia and Callenberg, Saxony, Germany . In: The Canadian Mineralogist . tape 38 , no. 6 , 2000, pp. 1467–1476 , doi : 10.2113 / gscanmin.38.6.1467 ( rruff.info [PDF; 1.6 MB ; accessed on November 26, 2017]).
Web links
Individual evidence
- ↑ Webmineral - Petterdite (English)
- ↑ a b c d e Petterdite . 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; 67 kB ]).
- ↑ a b c d e Petterdite at mindat.org (English)
- ↑ Stefan Weiß: The large Lapis mineral directory . 5th edition. Christian Weise Verlag, Munich 2008, ISBN 3-921656-17-6 .