Pyroxferroit
| Pyroxferroit | |
|---|---|
| General and classification | |
| other names |
IMA 1970-001 |
| chemical formula |
|
|
Mineral class (and possibly department) |
Silicates and Germanates - chain silicates and band silicates (inosilicates) |
|
System no. to Strunz and to Dana |
9.DO.05 ( 8th edition : VIII / F.31) 65.06.01.02 |
| Crystallographic Data | |
| Crystal system | triclinic |
| Crystal class ; symbol | triclinic pinacoidal; 1 |
| Space group | P 1 (No. 2) |
| Lattice parameters |
a = 6.63 Å ; b = 7.56 Å; c = 17.38 Å α = 114.3 °; β = 82.7 °; γ = 94.6 ° |
| Formula units | Z = 2 |
| Physical Properties | |
| Mohs hardness | 5 to 6 |
| Density (g / cm 3 ) | measured: 3.68 to 3.76; calculated: 3.82 to 3.83 |
| Cleavage | completely according to {110} and {1 1 0}, indistinct according to {010} and {001} |
| colour | colorless, light to dark yellow, light orange to orange-pink, light brown to gray-black |
| Line color | White |
| transparency | transparent to translucent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.746 to 1.756 n β = 1.750 to 1.758 n γ = 1.764 to 1.768 |
| Birefringence | δ = 0.018 |
| Optical character | biaxial positive |
| Axis angle | 2V = 30 ° to 40 ° (measured); 50 ° to 58 ° (calculated) |
| Other properties | |
| Chemical behavior | insoluble in acids, easily fusible into a magnetic pearl |
Pyroxferroit is a rarely occurring mineral from the mineral class of "silicates and germanates" with the idealized chemical composition Fe 2+ SiO 3 and is therefore chemically an iron silicate. Structurally , pyroxferroit belongs to the chain silicates .
Pyroxferroit crystallizes in the triclinic crystal system , but develops only weak crystals and millimeter-sized individual grains with a glass-like sheen on the surfaces.
With pyroxmangite , pyroxferroite forms a seamless series of mixed crystals . Therefore, the mixed formula (Fe 2+ , Mn) 7 [Si 7 O 21 ] is given for the iron-rich pyroxferroite in various sources . The elements iron and manganese indicated in round brackets can represent each other in the formula ( substitution , diadochie), but are always in the same proportion to the other components of the mineral.
In its pure form, pyroxferroit is colorless and transparent. However, through the addition of foreign admixtures or mixed crystal formation with pyrox mangite, it can also take on a light to dark yellow, light orange to orange-pink or light brown to gray-black color, with the transparency correspondingly decreasing.
Etymology and history
Pyroxferroit was first discovered as a natural mineral formation in samples of the lunar rock from Mare Tranquillitatis , which the Apollo 11 mission brought from the moon in 1969 . The rock and the newly discovered mineral were analyzed and described by a research team consisting of Edward Ching-Te Chao , Jean A. Minkin, Clifford Frondel , Cornelius Klein Jr., John C. Drake, Louis Fuchs, Benjamin Tani, Joseph V. Smith, Alfred T. Anderson, Paul B. Moore, GR Zechman Jr., Robert James Traill, AG Plant, JAV Douglas, and Michael R. Dence. They named it on the one hand based on the crystal structure similar to the pyroxene group and the iron contained in the compound ( Latin ferrum , prefix ferro ) and on the other hand because of the relationship with pyroxmangite .
However, as a synthetic product in slag that is produced during the smelting of iron, the compound had long been known and was called iron rhodonite .
Type material of the mineral is stored at the Lunar Science Institute in Houston, Texas.
classification
Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the pyroxferroit belonged to the mineral class of "silicates and germanates" and there to the department of "chain silicates and band silicates (inosilicates)", where together with plumalsite and pyrox mangite it was named " Pyroxmangite group "with the system no. VIII / F.31 .
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 classifies pyroxferroit into the category of "chain and band silicates". This is, however, further subdivided according to the structure of the chains, so that the mineral can be found in the sub-section "Chain and band silicates with 7-, 8-, 10-, 12- and 14-periodic chains" according to its structure, where it can be found also together with pyrox mangite the "pyrox mangite group" with the system no. 9.DO.05 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns pyroxferroit to the class of "silicates and germanates" and there in the department of "chain silicate minerals". Here it is also in the "Pyroxmangite group" with the system no. 65.06.01 to be found in the subsection “ Chain silicates: Simple unbranched chains, W = 1 with chains P = 7 ”.
Chemism
The idealized composition of pyroxferroite is given as Fe 2+ SiO 3 , due to the mixed crystal formation with pyroxmangite, pyroxferroite always contains a small amount of manganese. Furthermore, can the calcium and magnesium as representatives of the iron and aluminum be included as representatives of the silicon.
The empirical formula for pyroxferroit is given in the original description from 1970 as (Fe 0.84 Ca 0.13 Mg 0.02 Mn 0.02 ) (Si 0.99 Al 0.01 ) O 3 and one year later by Charles W. Burnham corrected to (Fe 0.83 Ca 0.13 Mg 0.02 Mn 0.02 ) SiO 3 .
Crystal structure
Pyroxferroite crystallizes triclinically in the space group P 1 (space group no. 2) with the lattice parameters a = 6.63 Å ; b = 7.56 Å; c = 17.38 Å; α = 114.3 °; β = 82.7 ° and γ = 94.6 ° as well as two formula units per unit cell .
The crystal structure consists of unbranched seven-single chains parallel to the c-axis, that is, the structure of the chain of corner-linked [SiO 4 ] tetrahedra is repeated after seven links. The coordination of the iron or manganese cations is similar to that of rhodonite .
properties
Pyroxferroit is insoluble in acids, but can easily be melted into a magnetic bead .
Modifications and varieties
The compound Fe 2+ SiO 3 is polymorphic and occurs in nature in addition to the triclinic pyroxferroite as ferrosilite in orthorhombic symmetry and as clinoferrosilite in monoclinic symmetry.
Education and Locations
Pyroxferroit forms in the form of individual grains in micro gabbros or diabase . Various clinopyroxes from the pyroxene group and plagioclase from the feldspar group as well as cristobalite , tridymite , fayalite , fluorapatite and ilmenite occur as accompanying minerals .
In addition to its type locality , the lunar rock from Mare Tranquillitatis, Pyroxferroit was found on Earth in some lunar meteorites , but also in Mars meteorites . Known meteorite finds so far (as of 2017) are the Mars meteorites QUE 94201 ( Viktorialand ) and EETA 79001 ( Elephant Moraine ) discovered in Antarctica , as well as a lunar ( Dhofar 287 ) and a Martian meteorite ( Dhofar 378 ) in Dhofar in Oman .
The only known site in Germany so far is the Caspar quarry on Ettringer Bellerberg in the Rhineland-Palatinate Eifel .
Other previously known sites are the Cannington mine in McKinlay Township in McKinlay Shire, Australia , some smaller sites near Kiviniemi in the municipality of Rautalampi and near Simpsiö near Lapua and Vittinki near Seinäjoki in Finland, the Isanago mines near Kyōtango and Ohnari near Mineyama-chō (since 2004 incorporated to Kyōtango) in the Japanese prefecture of Kyōto , a manganese-iron deposit near Răzoare in the Romanian district of Maramureș , the Väster Silvberg near Smedjebacken in the Swedish province of Dalarnas län and the "Franklin Mine" near Franklin (New Jersey) and the place Iva in Anderson County (South Carolina) in the USA.
See also
literature
- Edward Ching-Te Chao, Jean A. Minkin, Clifford Frondel, Cornelius Klein Jr., John C. Drake, Louis Fuchs, Benjamin Tani, Joseph V. Smith, Alfred T. Anderson, Paul B. Moore, GR Zechman Jr., Robert James Traill, AG Plant, JAV Douglas, Michael R. Dence: Pyroxferroite, a new calcium-bearing iron silicate from Tranquility Base . In: Geochimica et Cosmochimica Acta, Supplemental Proceedings of the Apollo XI Lunar Science Conference . tape 1 , 1970, p. 65–79 ( rruff.info [PDF; 1.9 MB ; accessed on August 7, 2017]).
- Michael Fleischer : New mineral names . In: American Mineralogist . tape 55 , 1970, pp. 2135–2139 ( rruff.info [PDF; 376 kB ; accessed on August 7, 2017]).
- Charles W. Burnham: The crystal structure of pyroxferroite from Mare Tranquillitatis . In: Proceedings of the Second Lunar Science Conference . tape 1 , 1971, p. 47–57 ( harvard.edu [PDF; 1,3 MB ; accessed on August 7, 2017]).
Web links
- Mineral Atlas: Pyroxferroit (Wiki)
- Webmineral - Pyroxferroite (English)
- RRUFF Database-of-Raman-spectroscopy - Pyroxferroite (English)
- American-Mineralogist-Crystal-Structure-Database - Pyroxferroite (English)
Individual evidence
- ↑ a b c IMA / CNMNC List of Minerals; September 2017 (PDF 1.67 MB)
- ↑ a b c d e Richard V. Gaines, H. Catherine W. Skinner, Eugene E. Foord, Brian Mason , Abraham Rosenzweig: Dana's New Mineralogy . 8th edition. John Wiley & Sons, New York (et al.) 1997, ISBN 0-471-19310-0 .
- ↑ a b c d e 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. 652 .
- ↑ Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties . 6th completely revised and supplemented edition. Weise, Munich 2014, ISBN 978-3-921656-80-8 .
- ↑ a b c Pyroxferroite . 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; 71 kB ]).
- ↑ a b c d e Mindat - Pyroxferroite (English)
- ^ Friedrich Klockmann : Klockmanns textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp. 734 (first edition: 1891).
- ↑ Find location list for Pyroxferroit at the Mineralienatlas and at Mindat