Papagoite

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Papagoite
Papagoite-k-152b.jpg
Papagite from the Sinclair Mine, Karas , Namibia
General and classification
chemical formula Ca 2 Cu 2 Al 2 [(OH) 6 | Si 4 O 12 ]
Mineral class
(and possibly department) 		Silicates and Germanates
System no. to Strunz
and to Dana 		9.CE.05 ( 8th edition : VIII / E.06)
60.01.04.01
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic 2 / m
Room group (no.) C 2 / m (No. 12)
Lattice parameters a  = 12.93  Å ; b  = 11.50 Å; c  = 4.70 Å
β  = 100.8 °
Formula units Z  = 2
Physical Properties
Mohs hardness 5 to 5.5
Density (g / cm 3 ) 3.25
Cleavage clearly after {100}
colour sky blue
Line color Light Blue
transparency transparent to translucent
shine Glass gloss
Crystal optics
Refractive indices n α  = 1.607
n β  = 1.641
n γ  = 1.672
Birefringence δ = 0.065
Optical character biaxial negative
Axis angle 2V = measured: 78 °; calculated: 84 °

The mineral papagoite is a very rare ring silicate with the chemical composition Ca 2 Cu 2 Al 2 [(OH) 6 | Si 4 O 12 ]. It crystallizes in the monoclinic crystal system and develops mostly sky-blue crystals up to about three millimeters in size, flattened after {100} . More common, however, are leafy or microcrystalline, radial-radial aggregates and crusty coatings or inclusions in quartz .

With a Mohs hardness of 5 to 5.5, papagite is one of the medium-hard minerals that, like the reference mineral apatite, can still be scratched with a knife. Visible crystal surfaces have a glass-like sheen .

Etymology and history

Papagoite was first discovered in the "New Cornelia Mine" (also Ajo Mine) near Ajo in Pima County in the US state of Arizona and described in 1960 by C. Osborne Hutton and Angelina C. Vlisidis, who named the mineral after the Tohono O. living in the area 'Odham (spanish Papago ) designated.

classification

In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , papagoite belonged to the mineral class of "silicates and germanates" and there to the department of " ring silicates (cyclosilicates)", where it formed an independent group together with ashburtonite .

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 papagoite to the class of "silicates and germanates" and there in the section of " ring silicates (cyclosilicates)". However, this section is further subdivided according to the type of silicate ring formation and the possible presence of further anions , so that the mineral according to its structure and its composition in the subdivision "[Si 4 O 12 ] 8− four-single rings without island-like, complex anions" is to be found where it is the only member of the unnamed group 9.CE.05 .

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns papagite to the class of "silicates and germanates" and there in the category of "ring silicates: rings of four". Here he is to be found as the only member of the unnamed group 60.01.04 within the sub-section " Ring Silicates: Rings of Four as Titanosilicates ".

Education and Locations

Papagite as inclusion in quartz from the "Messina Mine", Musina , Limpopo, South Africa

Papagoite forms as a secondary mineral in small veinlets within granodiorite - porphyry , mostly in paragenesis with Ajoit , Aurichalcit , barite , quartz and Shattuckit .

Altogether, papagoite has so far (status: 2011) been found at 7 sites. In addition to the “New Cornelia Mine” (Ajo Mine) type locality near Ajo in the USA, there are also the “Sinclair Mine” in the Karas region in Namibia, Košice in Eastern Slovakia and the “Messina Mine” (Musina Mine) and the vicinity of Musina in South Africa.

Crystal structure

Papagoite crystallizes monoclinically in the space group C 2 / m (space group no. 12) with the lattice parameters a  = 12.93  Å ; b  = 11.50 Å; c  = 4.70 Å and β = 100.8 ° and 2 formula units per unit cell .

See also

Individual evidence

  1. ↑ a b c d e Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X .
  2. ↑ Webmineral - Papagoite (English)
  3. ↑ a b c d Papagoite at mindat.org (English)

literature

  • C. Osborne Hutton and Angelina C. Vlisidis: Papagoite, a new copper-bearing mineral from Ajo, Arizona , in: The American Mineralogist , Vol. 45, May-June 1960 ( PDF 772.3 kB )

Web links

Commons : Papagoite  - collection of images, videos and audio files