Langit

Langit
	Langite (image width: 5 mm) ; Location: Old dumps from Richtarova, Stare Hory, Špania Dolina, Slovakia
General and classification
chemical formula	Cu 4 [(OH) 6 \| SO 4 ] • 2H 2 O
Mineral class; (and possibly department)	Sulphates, selenates, tellurates, chromates, molybdates, tungstates
System no. to Strunz ; and to Dana	7.DD.10 ( 8th edition : VI / D.03) ; 04/31/03/01
Similar minerals	Posnjakit , Wroewolfeit
Crystallographic Data
Crystal system	monoclinic (pseudo-orthorhombic or pseudo-hexagonal)
Crystal class ; symbol	monoclinic; m
Space group	Pa (No. 7, position 3)
Lattice parameters	a = 11.21 Å ; b = 6.03 Å; c = 7.12 Å ; β = 90.0 °
Formula units	Z = 2
Frequent crystal faces	{001}, {010}, {100}, {110}, {021}
Twinning	after {110} repeat twins with snowflake or star shape
Physical Properties
Mohs hardness	2.5 to 3
Density (g / cm 3 )	measured: 3.28 to 3.34; calculated: 3.26 to 3.37
Cleavage	according to {001} and {010}
Break ; Tenacity	uneven
colour	sky blue to bluish green
Line color	Light Blue
transparency	translucent
shine	Glass gloss to silk gloss
Crystal optics
Refractive indices	n α = 1.708 ; n β = 1.760 ; n γ = 1.798
Birefringence	δ = 0.090
Optical character	biaxial negative
Axis angle	2V = measured: 65 °; calculated: 78 °
Pleochroism	visible: X = c = light yellow-green; Y = b = blue green; Z = a = sky blue
Other properties
Chemical behavior	Easily soluble in acids and ammonia, not soluble in water

Langite is a rather seldom occurring mineral from the mineral class of " sulfates (and relatives)" with the chemical composition Cu ₄ [(OH) ₆ | SO ₄ ] · 2H ₂ O and is therefore chemically a water-containing copper sulfate with additional hydroxide ions .

Langite crystallizes in the monoclinic crystal system , but usually only develops small crystals up to about 7 mm in length, granular crusts or earthy to massive mineral aggregates of sky-blue to blue-green color with light blue streak color .

Langite also often forms pseudo-orthorhombic or pseudo-hexagonal repeat twins in the shape of snowflakes or stars. Due to its similarity in color and habit, there is a risk of confusion with Posnjakit and Wroewolfeit .

Etymology and history

Langite was first found in 1864 in the copper mine "Fowey Consols" (Tywardreath, Par Parish) near St Austell in the English county of Cornwall (United Kingdom) and described by Mervyn Herbert Nevil Story-Maskelyne (1823-1911), who owned the mineral named after the Viennese physicist Victor von Lang (1838–1921).

classification

In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the langite belonged to the mineral class of "sulfates, selenates, tellurates, chromates, molybdates, tungstates" and there to the department of "water-containing sulfates with foreign anions ", where it belongs together with Christelit , Guarinoit , Ktenasit , Nakauriit , Namuwit , Posnjakit , Ramsbeckit , Redgillit , Schulenbergit , Thérèsemagnanit and Wroewolfeit formed a distinct group.

The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the IMA, also assigns the langite to the class of "sulfates (selenates, tellurates, chromates, molybdates and tungstates)" and then to the "sulfates (selenates, etc.)" category .) with additional anions, with H ₂ O “. However, this section is further subdivided according to the size of the cations involved and the crystal structure, so that the mineral can be found accordingly in the sub-section "with medium-sized cations and layers of edge-sharing octahedra", where it is found together with guarinoite, posnjakite, schulenbergite, thérèsemagnanite, Wroewolfeit forms the unnamed group 7.DD.10 .

The systematics of minerals according to Dana assigns the langite to the class of "sulfates, chromates, molybdates" and there in the department of "hydrated sulfates with hydroxyl or halogen". Here he is the only member of the unnamed group 04/31/03 within the subdivision of " Hydrated sulfates with hydroxyl or halogen with (A ⁺ B ²⁺ ) ₄ (XO4) Z _q • x (H ₂ O) ".

Crystal structure

Langite crystallizes monoclinically in the space group Pa (space group no. 7, position 3) with the lattice parameters a = 11.21 Å ; b = 6.03 Å; c = 7.12 Å and β = 90.0 ° and 2 formula units per unit cell . Template: room group / 7.3

Modifications and varieties

The compound Cu ₄ [(OH) ₆ | SO ₄ ] • 2H ₂ O is dimorphic , that is, it occurs in nature in addition to the monoclinically crystallizing langite as also monoclinic, but with different lattice parameters , crystallizing wroewolfeit .

Education and Locations

Massive aggregate from Langit from Schwaz, Tyrol

Langit formed secondarily in the oxidation zone of copper sulfide - deposits . Accompanying minerals include brochantite , chalcophyllite , connellite , devillin , gypsum , malachite , posnyakite, serpierite and wroewolfeit.

So far (as of 2010), Langit has been found at more than 400 sites worldwide, including in Egypt , Australia , Belgium , Bolivia , Germany , France , Greece , Ireland , Italy , Japan , Canada , Morocco , Moldova , Namibia , New Zealand , Norway , Austria , Poland , Portugal , Sweden , Switzerland , Slovakia , Slovenia , Spain , South Africa , the Czech Republic , Ukraine , the United Kingdom (Great Britain) and the United States (USA).

literature

Paul Ramdohr , Hugo Strunz : Klockmann's textbook of mineralogy . 16th edition. Ferdinand Enke Verlag, 1978, ISBN 3-432-82986-8 , pp. 614 .
Petr Korbel, Milan Novák: Encyclopedia of Minerals . Nebel Verlag GmbH, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 147 .

Web links

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

Mineral Atlas: Langite (Wiki)
American Mineralogist Crystal Structure Database - Langite (English, 1984)

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. 401 .
↑ Webmineral - Langite (English)
↑ ^a ^b ^c ^d Langite . 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; 67 kB ; accessed on May 4, 2018]).
↑ ^a ^b ^c ^d ^e Langite at mindat.org (English)
↑ Dictionary of National Biography , Volume III "Neil-Young" (replica), originally published by Smith, Elder & Co., London 1912, ISBN 0-543-88108-3 (available online from Google Book Search )
^ T. Rupert Jones, Henry Woodward: Notices of recent discoveries. New Cornish mineral "Langite" . In: The Geological Magazine . tape 1 , 1864, p. 48 ( rruff.info [PDF; 163 kB ; accessed on May 4, 2018]).
↑ List of localities for Langite in the Mineralienatlas and Mindat

[StrunzNickel-1] 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. 401 .

[Webmineral-2] Webmineral - Langite (English)

[Datenblatt-3] Langite . 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; 67 kB ; accessed on May 4, 2018]).

[Mindat-4] Langite at mindat.org (English)

[DictNatBio-Story-Maskelyne-5] Dictionary of National Biography , Volume III "Neil-Young" (replica), originally published by Smith, Elder & Co., London 1912, ISBN 0-543-88108-3 (available online from Google Book Search )

[GeoMag-Langite-6] T. Rupert Jones, Henry Woodward: Notices of recent discoveries. New Cornish mineral "Langite" . In: The Geological Magazine . tape 1 , 1864, p. 48 ( rruff.info [PDF; 163 kB ; accessed on May 4, 2018]).

[Fundorte-7] List of localities for Langite in the Mineralienatlas and Mindat