Clinochlor
| Clinochlor | |
|---|---|
 |
|
| General and classification | |
| other names |
|
| chemical formula | (Mg, Fe 2+ , Al) 3 [(OH) 2 | AlSi 3 O 10 ] · (Mg, Fe 2+ , Al) 3 (OH) 6 |
|
Mineral class (and possibly department) |
Silicates and Germanates |
|
System no. to Strunz and to Dana |
9.EC.55 ( 8th edition : VIII / H.23) April 71, 01.04 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Space group | C 2 / m (No. 12) |
| Lattice parameters |
a = 5.35 Å ; b = 9.27 Å; c = 14.27 Å β = 96.3 ° |
| Formula units | Z = 2 |
| Physical Properties | |
| Mohs hardness | 2 to 2.5 |
| Density (g / cm 3 ) | measured: 2.60 to 3.02; calculated: 2.628 |
| Cleavage | completely after {001} |
| Break ; Tenacity | uneven |
| colour | colorless, white, gray, brown, yellowish, greenish, bluish, red-violet |
| Line color | White |
| transparency | transparent to translucent |
| shine | Glass gloss, pearlescent gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.571 to 1.588 n β = 1.571 to 1.589 n γ = 1.576 to 1.599 |
| Birefringence | δ = 0.005 to 0.011 |
| Optical character | biaxial positive |
| Pleochroism | Visible: X = light yellow- green to light blue-green Y = Z = light greenish- yellow to light blue- green |
Clinochlore (also clinochlore or Ripidolith ) is a very common mineral from the mineral class of " silicates and Germanates ". It crystallizes in the monoclinic crystal system with the chemical composition (Mg, Fe 2+ , Al) 3 [(OH) 2 | AlSi 3 O 10 ] • (Mg, Fe 2+ , Al) 3 (OH) 6 and develops mostly tabular to leafy or radial crystals , but also massive aggregates.
Etymology and history
The name is a combination of the Greek words clino based on the inclined optical axis of the mineral and chloros due to its typical green color. Clinochlor was first found and described in 1851 in West Chester (Pennsylvania) by William Phipps Blake .
classification
In the old systematics of minerals according to Strunz (8th edition) , clinochlor is in the section of layered silicates (phyllosilicates) and there in the chlorite group . The new system of minerals according to Strunz also sorts the clinochlor into layered silicates, but divides this department even more finely. Thus, the mineral now belongs to the phyllosilicates with mica tablets, composed of tetrahedral and octahedral networks .
In the systematics of minerals according to Dana , the clinochlor also belongs to the phyllosilicates, but is assigned to the group phyllosilicates Sheets of Six-Membered Rings interlayered 1: 1, 2: 1, and octahedra .
Crystal structure
Clinochlor crystallizes monoclinically in the space group C 2 / m (space group no. 12) with the lattice parameters a = 5.35 Å ; b = 9.27 Å; c = 14.27 Å and β = 96.3 ° and 2 formula units per unit cell .
properties
Pure clinochlor is colorless, but it can take on different colors due to foreign admixtures. A greenish-white to black-green color (name!) Is predominant, but white, gray, brown, yellowish and red-violet color varieties have also been found so far. The crystals are transparent to translucent and have a glass luster on the surfaces, whereas on the fractured surfaces or if they have a fibrous structure, mother-of-pearl to silk sheen. Its Mohs hardness is 2 to 2.5 and a density of 2.55 to 2.75 g / cm³.
Modifications and varieties
- As delessite and Diabantit be iron-rich varieties called by Clinochlore.
-
Kämmererit is a chromium-containing variety of clinochlor that is coveted by collectors due to its bright, peach-blossom-red color and named after August Alexander Kämmerer , the German mine director in St. Petersburg .
- Are more synonyms for chromium Klinochlorvarietäten Chromochlorit , Kotschubeit , Rhodochromit , Rhodophyllit and Septekämmererit .
- Leuchtenbergit is the name of a low-iron variety of clinochlorine.
- Pennin is a black-green color variant due to magnesium enrichment.
- As Sheridanit is called an aluminum-rich Clinochlore-variety.
Maufite , on the other hand, is a mixture of clinochlor and lizardite in the finest alternating layers .
Education and Locations
Clinochlor forms through hydrothermal metamorphosis in slate or marble . Accompanying minerals are biotite , chondrodite and magnetite .
In addition to its type locality in West Chester in Pennsylvania, it was found among others Achmatowsk am Ural , Slatoust , Schwarzenstein in Tirol , Traversalla in Piedmont and Markt-Laugast in Upper Franconia .
See also
literature
- WP Blake: Optical and blowpipe examination of the supposed chlorite of Chester County, Pa. In: American Journal of Science and Arts . tape 12 , 1851, pp. 339–341 ( rruff.info [PDF; 193 kB ; accessed on March 14, 2017]).
- Petr Korbel, Milan Novák: Encyclopedia of Minerals . Nebel Verlag GmbH, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 256 .
Web links
- Mineral Atlas: Clinochlor (Wiki)
- RRUFF Database-of-Raman-spectroscopy - Clinochlore (English)
- Clinochlore (English)
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. 672 .
- ↑ Webmineral - Clinochlore (English)
- ↑ a b Clinochlore . 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; 78 kB ; accessed on March 14, 2017]).
- ↑ a b c d e Mindat - Clinochlore (English)
- ↑ Mindat - Chromian Clinochlore (English)
- ↑ Stefan Weiß: The large Lapis mineral directory . 5th edition. Christian Weise Verlag, Munich 2008, ISBN 3-921656-17-6 .
- ↑ Find location list for clinochlor in the Mineralienatlas and Mindat