Scorzalith
| Scorzalith | |
|---|---|
 |
|
| General and classification | |
| other names |
Skorzalith |
| chemical formula | Fe 2+ Al 2 [(OH) 2 | (PO 4 ) 2 ] |
|
Mineral class (and possibly department) |
Phosphates, arsenates and vanadates |
|
System no. to Strunz and to Dana |
8.BB.40 ( 8th edition : VII / B.08) 10.41.01.02 |
| Similar minerals | Azurite , lazulite |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Room group (no.) | P 2 1 / c (No. 14) |
| Lattice parameters |
a = 7.15 Å ; b = 7.31 Å; c = 7.25 Å β = 120.6 ° |
| Formula units | Z = 2 |
| Twinning | multiple and lamellar twins |
| Physical Properties | |
| Mohs hardness | 5.5 to 6 |
| Density (g / cm 3 ) | measured: 3.33; calculated: 3.32 |
| Cleavage | good after {110}, indistinct after {101} |
| Break ; Tenacity | shell-like to uneven |
| colour | dark blue to greenish blue, rarely also purple |
| Line color | white to light blue |
| transparency | transparent to translucent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.626 to 1.645 n β = 1.654 to 1.674 n γ = 1.663 to 1.680 |
| Birefringence | δ = 0.037 |
| Optical character | biaxial negative |
| Axis angle | 2V = 62 ° (measured); 58 to 68 ° (calculated) |
| Pleochroism | visible: X = colorless; Y = Z = blue |
Scorzalith is a rarely occurring mineral from the mineral class of "phosphates, arsenates and vanadates". It crystallizes in the monoclinic crystal system with the idealized chemical composition Fe 2+ Al 2 [(OH) 2 | (PO 4 ) 2 ] and is therefore chemically an iron - aluminum - phosphate with additional hydroxide ions .
Scorzalite is the iron analogue of lazulite (MgAl 2 [(OH) 2 | (PO 4 ) 2 ]) and forms a complete mixed crystal row with it . Therefore, the mixed formula (Fe 2+ , Mg) Al 2 [(OH) 2 | (PO 4 ) 2 ] is occasionally given in various sources , whereby the elements indicated in the round brackets can represent each other ( substitution , diadochie), however, they are always in the same proportion to the other components of the mineral.
The mineral usually develops prismatic crystals and multiple or lamellar twins , but also occurs in the form of granular to massive mineral aggregates . The transparent to translucent crystals are deep blue to blue-green in color and have a glass-like sheen on the surface . Scorzalith leaves a white line on the whiteboard .
Etymology and history
Scorzalith was first discovered in the Córrego Frio Mine near Linópolis (municipality of Divino das Laranjeiras ) in the Brazilian state of Minas Gerais and described in 1949 by William Thomas Pecora (1913–1972) and Joseph John Fahey (1901–1980), who used the mineral in honor of Mineralogist Evaristo Pena Scorza (1899–1969) named.
Type material of the mineral is found in the Natural History Museum in London, England (Catalog No. 1965,207), Harvard University in Cambridge, Massachusetts (Catalog No. 100679) and the National Museum of Natural History in Washington, DC, USA (Catalog no. C5862).
classification
Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the scorzalite belonged to the mineral class of "phosphates, arsenates and vanadates" and there to the department of "anhydrous phosphates, with foreign anions F, Cl, O, OH", where, together with Barbosalith , Hentschelit , Lazulith , Lipscombit , Richellit , Trolleit , Wilhelmkleinit and Zinklipscombit, he created the " Lazulite Group" with the system no. VII / B.08 .
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 Scorzalith to the category 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 other anions (OH etc.) to the phosphate, arsenate or vanadate complex (RO 4 ), so that the mineral according to its composition in the sub-section “With exclusively medium-sized cations; (OH etc.): RO 4 ≤ 1: 1 “can be found, where together with Barbosalith, Hentschelit, Lazulith and Wilhelmkleinit the“ Lazulithgruppe ”with the system no. 8.BB.40 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the scorzalith to the class of "phosphates, arsenates and vanadates" and there in the department of "anhydrous phosphates etc., with hydroxyl or halogen". Here he is also in the " lazulith group " with the system no. 41.10.01 within the subsection “Anhydrous phosphates etc., with hydroxyl or halogen with (A 2+ B 2+ ) 3 (XO 4 ) 2 Z q ”.
Education and Locations
Like lazulite, scorzalite is a typical secondary mineral that forms through hydrothermal processes in granitic pegmatites or in kyanite-rich quartzites , where it displaces and replaces primary phosphates. In addition to quartz , various apatites , berlinite , feldspar , lacroixite , muscovite , souzalite , triphyline , trolleite , various tourmalines and wyllieite can occur as accompanying minerals .
As a rare mineral formation, Scorzalith could only be proven at a few localities, whereby so far (as of 2014) around 60 localities are known. In addition to its type locality Córrego Frio Mine near Linópolis, the mineral was only found in Brazil in the Gentil mine near Mendes Pimentel in Minas Gerais.
In Germany, Scorzalith has so far only been found at the Hennenkobel ( Hühnerkobel ) near Rabenstein (Zwiesel) and at the Frauenau drinking water reservoir in Lower Bavaria and in the Hagendorf- Süd pit (Markt Waidhaus ) in the Upper Palatinate.
The only known site in Austria so far is the Hahnenkofel near Lake Millstatt in Carinthia. In Switzerland, too, only one site is known to date with the Pontetal (Valle di Ponte) near Brissago TI in the canton of Ticino.
The pits Palermo No. 1 and 2 near Groton in Grafton County of the US state of New Hampshire, where dark blue, granular aggregates with a diameter of up to 10 centimeters emerged, are known for their extraordinary scorzalite finds.
Other locations are in Afghanistan, Australia, Bolivia, France, Japan, Canada, Morocco, Namibia, Portugal, Rwanda, Russia, Sweden, Spain, the Czech Republic and in various states of the USA.
Crystal structure
Scorzalith crystallizes monoclinically in the space group P 2 1 / c (space group no. 14) with the lattice parameters a = 7.15 Å ; b = 7.31 Å; c = 7.25 Å and β = 120.6 ° and two formula units per unit cell .
use
For commercial use as a gem stone , scorzalite is of secondary importance despite its sometimes clear crystals and intense blue to blue-green color (purple scorzalite are rarely found). However, it is occasionally offered to collectors in various facet cuts.
See also
literature
- William T. Pecora and Joseph J. Fahey: The Corrego Frio pegmatite, Minas Gerais: scorzalite and souzalite, two new phosphate minerals. In: American Mineralogist. Volume 34, 1949, pp. 83-93 ( PDF 711.2 kB )
- WT Pecora and JJ Fahey: The lazulite-scorzalite isomorphous series. In: American Mineralogist. Volume 35, 1950, pp. 1–18 ( PDF 1.1 MB )
Web links
- Mineral Atlas: Scorzalith (Wiki)
- Webmineral - Scorzalite
- American-Mineralogist-Crystal-Structure-Database - Scorzalite
Individual evidence
- ↑ a b c Petr Korbel, Milan Novák: Mineral Encyclopedia . Nebel Verlag GmbH, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 162 ( Dörfler Natur ).
- ↑ a b c d e f Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 445 .
- ↑ Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties . 5th completely revised and supplemented edition. Weise, Munich 2008, ISBN 978-3-921656-70-9 .
- ↑ a b c Scorzalite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 65.4 kB )
- ^ A b Walter Schumann: Precious stones and gemstones. All species and varieties in the world. 1600 unique pieces . 13th revised and expanded edition. BLV Verlags-GmbH., Munich et al. 2002, ISBN 3-405-16332-3 , p. 236 .
- ↑ a b c d Mindat - Scorzalite
- ^ Charles A. Anderson: William Thomas Pecora February 1, 1913 - July 19, 1972 , National Academy of Sciences, Washington DC 1975 ( PDF 2.4 MB )
- ↑ Faheyite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 63.6 kB )
- ^ William T. Pecora and Joseph J. Fahey: The Corrego Frio pegmatite, Minas Gerais: scorzalite and souzalite, two new phosphate minerals. In: American Mineralogist. Volume 34, 1949, pp. 83-93 ( PDF 711.2 kB )
- ↑ Mindat - Number of localities for Scorzalith
- ↑ Find location list for Scorzalith at the Mineralienatlas and at Mindat