Connellit

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Connellit
Connellite-87344.jpg
Well developed connellite needles from the Ingadanais mine near Vila Velha de Ródão , Castelo Branco, Portugal (field of view 7 mm)
General and classification
chemical formula Cu 19 [Cl 4 (OH) 32 | SO 4 ] • 2H 2 O
Mineral class
(and possibly department) 		Halides (according to Strunz); Sulfates (according to Dana)
System no. to Strunz
and to Dana 		3.DA.25 ( 8th edition : III / D.03)
01/31/01/01
Similar minerals Agardite , azurite , chrysocolla , cyanotrichite , shattuckite
Crystallographic Data
Crystal system Hexagonal
Crystal class ; symbol dihexagonal-dipyramidal 6 / m 2 / m 2 / m
Space group P 6 3 / mmc
Lattice parameters a  = 15.787  Å ; c  = 9.102 Å
Formula units Z  = 2
Physical Properties
Mohs hardness 3
Density (g / cm 3 ) 3.36 to 3.41
Cleavage no
Break ; Tenacity shell-like
colour blue, bluish green
Line color greenish blue
transparency translucent
shine Glass gloss
Crystal optics
Refractive indices n ω  = 1.724 to 1.738
n ε  = 1.746 to 1.758
Birefringence δ = 0.022
Optical character uniaxial positive

Connellite is a rather seldom occurring mineral from the mineral class of " halides ". It crystallizes in a hexagonal crystal system with the chemical composition Cu 19 [Cl 4 (OH) 32 | SO 4 ] • 2H 2 O and usually develops dense groups of fine-fiber to needle-like, radial- rayed crystal clusters of a few millimeters in size, which are usually according to [0001] are stretched and streaked. Bulky aggregates and crusty coatings from Connellit are also known. The color varies from light to blue green.

Connellite forms a mixed series with buttgen bachite .

Etymology and history

Connellite was first found in 1842 in the "Providence Mine" at Carbis Bay / Lelant in the English county of Cornwall and described by Rashleigh, who named the mineral after Arthur Connell (1794–1863), a Scottish chemist who was the first to investigate the mineral.

classification

In the meantime outdated, but still in use 8th edition of the mineral classification by Strunz of Connellit belonged to the mineral class of "halides" and then to the Department of "oxyhalides" where he along with Buttgenbachit , Claringbullit , Gordait , Khaidarkanit and Simonkolleit formed an independent group .

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 the connellite to the class of "halides" and there in the department of "oxyhalides, hydroxyhalides and related double halides" . This section is, however, further subdivided according to the dominant cation in the compound, so that the mineral can be found in the sub-section “With Cu etc., without Pb”, where it only belongs to the unnamed group 3.DA together with buttgenbachite .25 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Connellite to the class of sulphates and there in the division of "water-containing sulphates with hydroxyl or halogen". Here the mineral is the only member of the unnamed group 31.01.01 within the subdivision " Water-containing sulfates with hydroxyl or halogen and the general formula (A + B 2+ ) m (XO 4 ) p Z q  • x (H 2 O), with the molar ratio m: p> 6: 1 “.

Education and Locations

Small Connellite crystal clusters on cuprite

Connellit forms as a secondary mineral in the oxidation zone of copper - deposits . There it is mostly associated with atacamite , azurite , botallackite , cuprite , langite , malachite and spangolite .

So far (as of 2010) Connellite has been detected at around 210 sites worldwide, including Algeria , Argentina , Australia , Belgium , Bolivia , Chile , Germany , France , Greece , Greenland , Ireland , Italy , Japan , the Democratic Republic of the Congo , Morocco , Namibia , New Zealand , Austria , Portugal , Spain , South Africa , the Czech Republic , Hungary , Uzbekistan , the United Kingdom (Great Britain) and the United States (USA).

Crystal structure

Connellite crystallizes hexagonally in the space group P 6 3 / mmc with the lattice parameters a  = 15.787  Å and c  = 9.102 Å as well as two formula units per unit cell .

See also

Individual evidence

  1. ↑ a b c d e Handbook of Mineralogy - Connellite (English, PDF 67.3 kB)
  2. ↑ a b American Mineralogist Crystal Structure Database - Connellite (English, 2006)
  3. ↑ a b Connellite at mindat.org (engl.)
  4. ↑ Stefan Weiß: The large Lapis mineral directory. 5th edition, Christian Weise Verlag, Munich 2008, ISBN 3-921656-17-6 .
  5. ↑ Mindat - Localities for Connellite
  6. ↑ American Mineralogist Crystal Structure Database - Connellite (English, 2006)

literature

Web links

Commons : Connellite  - collection of pictures, videos and audio files