Rosasite

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Rosasite
Rosasite-Calcite-278338.jpg
Fine-needle rosasite (blue-green) on calcite (colorless) from the Ojuela Mine, Durango, Mexico
General and classification
chemical formula (Cu, Zn) 2 [(OH) 2 | CO 3 ]
Mineral class
(and possibly department) 		Carbonates and nitrates
System no. to Strunz
and to Dana 		5.BA.10 ( 8th edition : V / C.01)
16a.03.01.01
Similar minerals Chrysocolla , turquoise
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic 2 / m
Space group P 2 1 / m
Lattice parameters a  = 9.37  Å ; b  = 12.12 Å; c  = 3.13 Å
β  = 90.1 °
Formula units Z  = 4
Twinning after {100}
Physical Properties
Mohs hardness 4.5
Density (g / cm 3 ) measured: 4.0 to 4.2; calculated: 4.15
Cleavage completely according to {010} and {100}
Break ; Tenacity shell-like
colour green, bluish green, sky blue
Line color blue green
transparency translucent to opaque
shine Glass gloss, silk gloss
Crystal optics
Refractive indices n α  = 1.672 to 1.688
n β  = 1.796 to 1.830
n γ  = 1.811 to 1.831
Birefringence δ = 0.139 to 0.143
Optical character biaxial negative
Axis angle 2V = measured: 33 °; calculated: 36 °
Pleochroism strong: X = light emerald green or colorless; Y and Z = dark emerald green or light blue
Other properties
Chemical behavior Soluble in acids with release of CO 2

Rosasite is a seldom occurring mineral from the mineral class of " carbonates and nitrates ". It crystallizes in the crystal system with the chemical composition (Cu, Zn) 2 [(OH) 2 | CO 3 ] and develops mostly translucent to opaque mineral aggregates with spherical, kidney and grape-like habit , consisting of needle-like to fibrous crystals between 0.5 and 1 cm ("Ojuela Mine", Mexico) size. The color of the rosasite fluctuates between green, blue-green and light blue, but the color of the streak is always blue-green. The individual crystal surfaces show a glass luster, but the corresponding mineral aggregate as a whole has a silky sheen .

Rosasite is very similar in color to the minerals chrysocolla and turquoise , but they have a different Mohs hardness . With a Mohs hardness of 2 to 4, chrysocolla is usually much softer and turquoise with 5 to 6 harder than rosasite with a Mohs hardness of 4.5.

Etymology and history

Rosasite was first discovered in 1908 in the "Rosas Mine" near Narcao in the Italian province of Carbonia-Iglesias (Sardinia). The mineral was named after this type of locality by D. Lovisato, who first described it.

The type material of the mineral is in the Muséum national d'histoire naturelle ( Natural History Museum, Paris ) under the registration number 109.327.

classification

In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the rosasite still belonged to the common mineral class of "carbonates, nitrates and borates " and there to the department of "anhydrous carbonates with foreign anions ", where together with azurite it was the independent "Azurite-Rosasite series" formed, to which aurichalcite , brianyoungite , georgeit , glaucomaite , hydrozincite , kolwezite , losyite , mcguinnessite , malachite , nullaginite , pokrovskite , sclarite and zinc rosasite were assigned.

The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), assigns rosasite to the new class of "carbonates and nitrates" (the borates now form a separate class). There it still belongs to the department of “Carbonates with additional anions; without H 2 O “( anhydrous carbonates with foreign anions ). However, this division is more precisely subdivided according to the dominant cations in the compound , so that the mineral can be found according to its composition in the sub-division "with Cu, Co, Ni, Zn, Mg, Mn", where it can be found together with Glaukosphärit, Kolwezit, Malachit, Mcguinnessit, Nullaginit, Pokrovskit, Rosasit and Zinc rosasite the "malachite group" with the system no. 5.BA.10 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the rosasite, like the old Strunz's systematics, to the common class of “carbonates, nitrates and borates”, but in the more finely subdivided division of “carbonates with hydroxyl or halogen” ". Here he is the namesake of the "Rosasitgruppe" with the system no. 16a.03.01 and the other members Glaukosphärite, Kolwezit, Zinc Rosasite and Mcguinnessite within the sub-section " Carbonates with hydroxyl or halogen and the general composition (AB) 2 (XO) 3 Z q ".

Education and Locations

Long-fiber rosasite (bluish white) and konichalcite (light green) from the "Mohawk Mine" (Mohawk Hill), California, USA
Impressive multiple paragenesis of wulfenite (orange), hemimorphite (colorless), rosasite (blue-green) and goethite (gray-black) from the 79 mine (79th mine) in the Dripping Spring Mountains , Gila County (Arizona, USA)

Rosasit forms as a typical secondary mineral in the oxidation zone of copper - and zinc - deposits , mostly in paragenesis with other secondary minerals such as, among others, azurite and malachite , Aurichalcit , Cerussite , Hemimorphite , Hydrozinkit , Konichalcit and Smithsonite .

So far (as of 2010) rosasite has been found at around 340 sites worldwide. In Germany, the mineral was found in several regions of the Black Forest and Upper Palatinate Forest , North Hesse , the Harz Mountains , North Rhine-Westphalia , Rhineland-Palatinate and the Saxon Ore Mountains . In Austria, rosasite was found in several regions of Carinthia , Salzburg , Styria and Vorarlberg . In Switzerland, the mineral has so far only appeared in Novaggio and in some regions of the canton of Valais .

Other locations are Argentina , Australia , Belgium , Bulgaria , Chile , China , Czech Republic , France , Greece , Iran , Ireland , Italy , Japan , Kazakhstan , Madagascar , Mexico , Namibia , Norway , Poland , Romania , Russia , Slovakia , Slovenia , Spain , South Africa , Tajikistan , Hungary , the United Kingdom (Great Britain) and the United States of America (USA).

The “Ojuela Mine” near Mapimí (Durango) in Mexico is particularly well-known, where spherical rosasite aggregates with needle-like crystals up to one centimeter in size came to light.

Crystal structure

Rosasite crystallizes monoclinically in the space group P 2 1 / m with the lattice parameters a  = 9.37  Å ; b  = 12.12 Å; c  = 3.13 Å and β = 90.1 ° and 4 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 - Rosasite (English)
  3. ↑ a b c d Rosasite at mindat.org (English)
  4. ↑ a b Catalog of Type Mineral Specimens, Commission on Museums (IMA) ( Memento of the original from October 26, 2004 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (English, PDF 65.4 kB; p. 10) @1@ 2Template: Webachiv / IABot / www.agiweb.org

literature

Web links

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