Ajoite
| Ajoite | |
|---|---|
 |
|
| General and classification | |
| chemical formula | (K, Na) Cu 7 Al [Si 9 O 24 (OH) 6 ] • 3H 2 O |
|
Mineral class (and possibly department) |
Silicates and germanates - unclassified silicates |
|
System no. to Strunz and to Dana |
9.EA.70 ( 8th edition : VIII / D.07) 78.05.01.01 |
| Crystallographic Data | |
| Crystal system | triclinic |
| Crystal class ; symbol | triclinic pinacoidal; 1 |
| Space group | P 1 (No. 1) or P 1 (No. 2) |
| Lattice parameters |
a = 13.64 Å ; b = 14.51 Å; c = 13.62 Å, α = 107.2 °; β = 105.4 °; γ = 110.6 ° |
| Formula units | Z = 3 |
| Physical Properties | |
| Mohs hardness | not defined |
| Density (g / cm 3 ) | measured: 2.96; calculated: 2.951 |
| Cleavage | completely after {010} |
| Break ; Tenacity | uneven, mussel-like |
| colour | bluish green |
| Line color | greenish white |
| transparency | translucent to opaque |
| shine | Glass gloss to matt |
| radioactivity | hardly measurable |
| Crystal optics | |
| Refractive indices |
n α = 1.550 n β = 1.583 n γ = 1.641 |
| Birefringence | δ = 0.091 |
| Optical character | biaxial positive |
| Axis angle | 2V = measured: 68 to 80 °; calculated: 76 ° |
| Pleochroism | visible: X = very light blue-green Y = shiny blue-green |
The mineral ajoite is a very rarely occurring layered silicate with the chemical composition (K, Na) Cu 7 Al [Si 9 O 24 (OH) 6 ] · 3H 2 O. It crystallizes in the triclinic crystal system and is mostly in the form of tufted, fibrous, lamellar or prismatic crystals up to about half a millimeter in length of bluish-green color with greenish-white streak color . As inclusions (inclusions) in quartz , it also gives it a greenish to bluish color.
Etymology and history
The blue-green copper-aluminum silicate was first discovered by Harry Berman ( Harvard University ) in August 1941 together with dark blue shattuckite in the "New Cornelia Mine ( Ajo Mine )" in the Little Ajo Mountains in Pima County (Arizona, USA). Berman tried to identify and describe the new mineral together with Waldemar Theodore Schaller , but died unexpectedly in 1944. Schaller finished the analyzes together with Angelina C. Vlisidis and named the mineral after its first place of discovery ( type locality ) ajoite.
classification
Already in the outdated but still in use 8th edition of the mineral classification by Strunz of Ajoit belonged to the mineral class of "silicates and Germanates" and then to the Department of "unclassified silicates", where he together with Whelanit the unnamed group VIII / D.07 formed .
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 ajoite to the class of "silicates and germanates", but there in the department of "phyllosilicates". This is further subdivided according to the crystal structure , so that the mineral can be found according to its structure in the sub-section "Simple tetrahedral networks with 4, 5, (6) and 8-membered rings", where it is the only member of the unnamed Forms group 9.EA.70 .
The systematics of minerals according to Dana also assigns the ajoite to the class of "silicates and germanates" and there in the department of "unclassified silicates". Here he is the only member of the unnamed group 78.05.01 within the subdivision of " Unclassified Silicates: Possible Layered Silicates ".
Crystal structure
Ajoite crystallizes triclinically in the space group P 1 (space group no. 1) or P 1 (no. 2) with the lattice parameters a = 13.64 Å ; b = 14.51 Å; c = 13.62 Å; α = 107.2 °; β = 105.4 ° and γ = 110.6 ° and 3 formula units per unit cell .
Education and Locations
Ajoit forms as a secondary mineral in copper - deposits . There he finds mostly with Shattuckit socialized or grown in quartz , but can also, depending on the locality with other accompanying minerals such as, but Konichalcit , the Bi- and Ca-containing, greenish yellow Mottramit -Varietät Duhamelit , muscovite , Papagoite , pyrite and sillenite occur.
In addition to its type locality Ajo Mountains, the mineral was also found in the "Potter-Cramer Mine" ( Vulture Mountains ), also located in Pima County , and in the "Moon Anchor Mine" ( Big Horn Mountains ).
In Germany, ajoite has so far only been found near Ramsbeck in the Sauerland. The only Austrian place of discovery is the Putzkammer Alp in the Verwall Group in Vorarlberg.
Other sites are the "Ashio Mine" near Ashio in the Japanese prefecture of Tochigi , Khorixas in Namibia, the "Messina Mine" near Messina (today: Musina ) in South Africa and Tavistock (Devon) in England (United Kingdom).
See also
literature
- WT Schaller, Angelina C. Vlisidis: Ajoite, a new hydrous Aluminum Copper Silicate . In: The American Mineralogist . tape 43 , 1958 ( minsocam.org [PDF; 291 kB ; accessed on April 15, 2018]).
- Petr Korbel, Milan Novák: Mineral Encyclopedia (= Villager Nature ). Nebel Verlag, Eggolsheim 2002, ISBN 978-3-89555-076-8 , p. 237 .
Web links
- Mineral Atlas: Ajoite (Wiki)
- RRUFF Database-of-Raman-spectroscopy - Ajoite (English)
- American-Mineralogist-Crystal-Structure-Database - Ajoite (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. 714 .
- ↑ Webmineral - Ajoite (English)
- ↑ a b c Ajoite . 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; 76 kB ; accessed on April 15, 2018]).
- ↑ a b 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 d e f g Mindat - Ajoite (English)
- ^ Mineral Atlas: Ajoite