Glaucochroit
| Glaucochroit | |
|---|---|
 |
|
| General and classification | |
| chemical formula | CaMn [SiO 4 ] |
|
Mineral class (and possibly department) |
Silicates and Germanates - island silicates |
|
System no. to Strunz and to Dana |
9.AC.05 ( 8th edition : VIII / A.05) March 51, 02.03 |
| 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 = 4.91 Å ; b = 11.15 Å; c = 6.49 Å |
| Formula units | Z = 4 |
| Twinning | Penetration u. Contact twins |
| Physical Properties | |
| Mohs hardness | ≈ 6 |
| Density (g / cm 3 ) | measured: 3,407; calculated: 3.465 |
| Cleavage | very indistinct after {001} |
| Break ; Tenacity | shell-like |
| colour | bluish-green, gray-violet, brown to brownish-pink, red-orange |
| Line color | White |
| transparency | translucent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.679 to 1.686 n β = 1.716 to 1.723 n γ = 1.729 to 1.736 |
| Birefringence | δ = 0.050 |
| Optical character | biaxial negative |
| Axis angle | 2V = 61 ° (measured); 60 ° (calculated) |
Glaucochroite is a rarely occurring mineral from the mineral class of "silicates and germanates" with the chemical composition CaMn [SiO 4 ] and is therefore chemically a calcium - manganese - silicate .
Glaucoma crystallizes in the orthorhombic crystal system and develops mostly granular to massive mineral aggregates , rarely also prismatic crystals with a length of up to 1 cm and a predominantly bluish-green color. Pink, white and brown glaucochroites are also known.
Etymology and history
The name Glaukochroit is a combination of two ancient Greek words. The first part of the word Glauko- from γλαυκός [glaukós] stands for the bright shine of the sky, the sea or the human eye, whereby the color is not precisely defined and can vary between gray, blue and green depending on the source. The second part of the word -chro (it) of χρώμα [chroma] means color. Put together, the name Glaukochroit refers to the predominantly bright, shiny, bluish-green color of the mineral.
Glaukochroit was first found in 1899 in the "Franklin Mine" near Franklin (New Jersey) in Sussex County of New Jersey in the USA. The mineral was scientifically described by Samuel Lewis Penfield (1856-1906) and CH Warren.
The type material of the mineral is available at Yale University in New Haven (Connecticut, USA) under catalog no. 2.4359 and 2.4360 kept.
classification
Already in the outdated, but partly still in use 8th edition of the mineral systematics according to Strunz , the glaucoma belonged to the mineral class of "silicates and germanates" and there to the department of "island silicates (nesosilicates)", where together with kirschsteinite and monticellite it belonged to the "monticellite- Row "with the system no. VIII / A.05 .
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 glaucoma into the category of "island silicates (nesosilicates)". However, this is further subdivided according to the possible presence of additional anions and the coordination of the cations , so that the mineral is classified according to its composition and structure in the subsection “Island silicates without additional anions; Cations in octahedral [6] he coordination "can be found, where together with fayalite , forsterite , cherry stoneite, laihunite , Liebenbergite and Tephroit the" olive group "with the system no. 9.AC.05 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns glaucoma to the class of "silicates and germanates" and there in the department of "island silicate minerals ". Here it is together with Kirschsteinite and Monticellit in the " Monticellit-Kirschsteinite series " with the system no. 51.03.02 to be found in the subsection “ Island silicates: SiO 4 groups with all cations only in octahedral [6] coordination”.
Crystal structure
Glaucoma crystallizes orthorhombically in the space group Pbnm (space group no. 62, position 3) with the lattice parameters a = 4.91 Å ; b = 11.15 Å and c = 6.49 Å as well as four formula units per unit cell .
Education and Locations
Glaukochroit forms metamorphic layered zinc - deposits in skarns as a contact metamorphosis between diabase and marble or lime -Silicatgesteinen with manganese ores . It occurs there in paragenesis with various minerals such as Andradite , calcite , Cuspidin , diopside , Esperit , Franklinite , Hardystonit , Hodgkinsonit , Klinoedrit , Leukophönicit , Nasonit , Tephroit , Willemit and Zincite on.
In addition to its type locality "Franklin Mine" in New Jersey (USA), Glaukochroit was found at 5 other sites: In the "Kanoiri Mine" near Kanuma on the Japanese island of Honshū ; in the "Kombat Mine" near Kombat in the Namibian region of Otjozondjupa ; in the Khibiny massif on the Russian Kola Peninsula ; in the “Wessels Mine” near Hotazel in the South African Kalahari ; as well as in the “Jakobsberg Mine” near Nordmark in the Swedish municipality of Filipstad .
See also
literature
- SL Penfield, CH Warren: Some new Minerals from the Zinc Mines at Franklin, NJ, and Note concerning the Chemical Composition of Ganomalite . In: The American Journal of Science . tape 8 , 1899, pp. 339–353 ( rruff.info [PDF; 662 kB ; accessed on April 12, 2018]).
- Peter B. Leavens, Pete J. Dunn, Donald M. Burt: Glaucochroite (olivine, CaMnSiO 4 ) from Franklin, New Jersey: Its composition, occurrence, and formation . In: American Mineralogist . tape 72 , 1987, pp. 423-428 ( minsocam.org [PDF; 679 kB ; accessed on April 12, 2018]).
- Friedrich Klockmann : Klockmann's textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp. 665 (first edition: 1891).
- 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 , pp. 1034 .
Web links
- Mineral Atlas: Glaukochroit (Wiki)
- American Mineralogist Crystal Structure Database - Glaucochroite (English, 1978)
Individual evidence
- ↑ 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. 539 .
- ↑ Webmineral - Glaucochroite (English)
- ↑ a b c d Glaucochroite . 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; 73 kB ; accessed on April 12, 2018]).
- ↑ a b c d e Mindat - Glaucochroite at mindat.org (English)
- ↑ Hans Lüschen: The names of the stones. The mineral kingdom in the mirror of language . 2nd Edition. Ott Verlag, Thun 1979, ISBN 3-7225-6265-1 , p. 197, 227 .
- ↑ Biographical Memoir of Samuel Lewis Penfield (English, PDF 1.23 MB)
- ↑ Find location list for Glaukochroit in the Mineralienatlas and in Mindat