Annabergit

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Annabergit
Annabergite-Grece-1.jpg
Annabergite crystals from Laurion (Attica) in Greece , image size: 20 mm, crystal size: approx. 4 mm
General and classification
chemical formula Ni 3 (AsO 4 ) 2 · 8H 2 O
Mineral class
(and possibly department) 		Water-containing phosphates without foreign anions
System no. to Strunz
and to Dana 		8.CE.40 ( 8th edition : VII / C.10a)
03/40/06/04
Crystallographic Data
Crystal system Monoclinic
Crystal class ; symbol monoclinic prismatic; 2 / m
Space group C 2 / m (No. 12)Template: room group / 12
Lattice parameters a  = 10.05  Å ; b  = 13.30 Å; c  = 4.72 Å
β  = 102.1 °
Formula units Z  = 2
Physical Properties
Mohs hardness 1.5 to 2.5
Density (g / cm 3 ) measured: 3.07; calculated: 3.146
Cleavage completely after {010}, indistinct after {100}, { 1 02}
Break ; Tenacity leafy, uneven
colour dark to light green, yellow-green, gray-green, gray
Line color light green to white
transparency translucent to opaque
shine Diamond luster, mother-of-pearl luster
Crystal optics
Refractive indices n α  = 1.622
n β  = 1.658
n γ  = 1.687
Birefringence δ = 0.065
Optical character biaxial negative

Annabergite , outdated also known as nickel bloom or nickel ocher , is a rather seldom occurring mineral from the mineral class of "phosphates, arsenates, vanadates" with the chemical composition Ni 3 (AsO 4 ) 2 · 8 H 2 O and is therefore chemically a nickel - arsenate .

Annabergite crystallizes in the monoclinic crystal system and develops needle-like to long prismatic or tabular crystals , but also fine-grain, massive or earthy mineral aggregates and crusty coatings. Its color varies between dark green, yellow green and light green. As the cobalt content increases, the color takes on an increasingly gray shade.

Etymology and history

Annabergite was first scientifically described and recognized as an independent mineral in 1852 by Henry James Brooke and William Hallowes Miller , who named the mineral "Annaberg" (today Annaberg-Buchholz ) after its place of discovery . It was discovered there in the “Teichgräber Flacher Ader” of the “Malwine” shaft in the Frohnau district . Due to its name, this place is also considered a type locality of the Annabergit.

The mineral was known and described about a century earlier. In 1758, in the initially anonymously published work Försök til Mineralogie (translated by Brünnich in 1770) , Axel Frederic Cronstedt described a greenish coating on nickel line ( cupernickel ), which he considers to be a kind of lime from nickel ; so a nickel oxide. He therefore calls this coating nickel ocher ( Ochra Niccoli ). For the nickel ocher Cronstedt does not give a place of discovery, but for the copper nickel, which is said to come from Saxony, Saalfeld and the cobalt mines to "Los in Helsingeland" (Swedish: Los kobolt grufvor i Färila socken och Helsingeland ).

Johan Gottschalk Wallerius describes the mineral in his work Systema mineralogicum in 1778 as "Niccolum colore viridi efflorescens", in English nickel bloom , but does not give any location.

An exact chemical analysis of Annabergite is only provided by Brooke and Miller, who describe it as a hydrous arsenate of nickel and an isomorphism with erythrin (Co 3 [AsO 4 ] 2  • 8H 2 O) and vivianite (Fe 3 [PO 4 ] 2  • 8 H 2 O), which is later confirmed. All three minerals crystallize in a monoclinic prismatic manner.

classification

Already in the outdated 8th edition of the mineral classification according to Strunz , the annabergite belonged to the mineral class of "phosphates, arsenates and vanadates" and there to the department of "water-containing phosphates, arsenates and vanadates without foreign anions ", where it belongs together with erythrin , Hörnesit , Köttigit , Parasymplesit and Vivianit the "Vivianit series" with the system no. VII / C.10a .

In the Lapis mineral directory according to Stefan Weiß, which, out of consideration for private collectors and institutional collections, is still based on this old form of Karl Hugo Strunz's system , the mineral was given the system and mineral number. VII / C.13-80 . In the "Lapis Classification" This also corresponds to the department "Water-containing phosphates, arsenates and vanadates without foreign anions" where Annabergit with Arupit , Barićit , Bobierrit , Cattiit , Erythrite, Hörnesit, Köttigit, Manganohörnesit , Pakhomovskyit , Parasymplesit and Vivianit a forms an independent but unnamed group (as of 2018).

The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and was updated by the International Mineralogical Association (IMA) until 2009, also classifies Annabergit under the category of “Phosphates, etc., without additional anions; with H 2 O “. However, this is further subdivided according to the relative size of the cations involved as well as the molar ratio of phosphate, arsenate or vanadate complex (RO 4 ) to crystal water (H 2 O), so that the mineral according to its composition can be found in the subsection “With medium-sized cations only; RO 4  : H 2 O ≤ 1 "is found, where it together with Arupit, 2.5 Babanekit , Barićit, Erythrin, Ferrisymplesit , Hörnesit, Köttigit, Manganohörnesit, Pakhomovskyit , Parasymplesit, Santabarbarait and Vivianit the" Vivianit group " with the system no. 8.CE.40 forms.

The systematics of minerals according to Dana , which is common in the English-speaking world , also assigns Annabergit to the class of "Phosphates, Arsenates and Vanadates", but there in the category of " Hydrous phosphates etc., with (A 2+ ) 3 (XO 4 ) 2 × x (H 2 O) ", where together with Arupit, Barićit, Erythrin, Köttigit, Parasymplesit, Hörnesit, Pakhomovskyit and Vivianit the" Vivianitgruppe "with the system no. 03/40/06 forms.

Crystal structure

Annabergite crystallizes in the monoclinic crystal system in the space group C 2 / m (space group no. 12) with the lattice parameters a  = 10.05  Å ; b  = 13.30 Å; c  = 4.72 Å and β = 102.1 ° as well as two formula units per unit cell . Template: room group / 12

properties

Annabergit is readily acid-soluble and easily melts to a gray ball in front of the soldering tube , with an arsenic odor rising.

Modifications and varieties

The variety Cabrerit contains additions of magnesium .

Education and Locations

Annabergite on siderite from Laurion, Greece

Annabergit is mainly formed by weathering in nickel deposits. Mainly microcrystalline, flaky coatings, but also coarse, earthy crusts form. Crystals are rarely found and are usually short and hair-shaped. It usually forms efflorescences on nickel lin (red nickel gravel) and nickel skutterudite (chloanthite).

Annabergit has been detected at around 330 sites worldwide (as of 2010), including Germany , Argentina , Australia , Bolivia , Chile , China , Finland , France , Greece , Iran , Ireland , Italy , Japan , Canada , Morocco , Mexico , Netherlands , New Zealand , Norway , Oman , Austria , Poland , Portugal , Romania , Russia , Sweden , Switzerland , Zimbabwe , Slovakia , Spain , South Africa , Czech Republic , Turkey , Hungary , the United Kingdom (Great Britain) and the United States (UNITED STATES).

Good mineral finds have been made in the Turkish community of Çukurören in the Keçiborlu district , in the Spanish Sierra Cabrera and near the Greek city of Laurion , where crystals up to about 5 mm in size were found. Annabergit tubers about 2 cm in size were recovered from the “Snowbird Mine” near Alberton ( Montana ) in the USA.

See also

literature

Web links

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

Individual evidence

  1. ^ David Barthelmy: Annabergite Mineral Data. In: webmineral.com. Accessed August 26, 2020 (English).
  2. ^ A b c 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.  481 (English).
  3. ↑ a b c Annabergite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 (English, handbookofmineralogy.org [PDF; 68  kB ; accessed on August 26, 2020]).
  4. ↑ a b c d Annabergite. In: mindat.org. Hudson Institute of Mineralogy, accessed August 26, 2020 .
  5. ^ Johan Gottschalk Wallerius : Systema mineralogicum, quo corpora mineralia in classes, ordines, genera et species suis cum varietatibus divisa, describuntur, atqve observationibus, experimentis et figures ænis illustratu . tape  2 . ex Officina Krausiana, Viennæ 1778, p. 191 (Latin, limited preview in Google Book search).
  6. ^ HJ Brooke, WH Miller: Elementary introduction to Mineralogy . Gilbert & Rivington, London 1852, pp. 503–504 (English, limited preview in Google Book Search).
  7. ↑ Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties. Status 03/2018 . 7th, completely revised and supplemented edition. Weise, Munich 2018, ISBN 978-3-921656-83-9 .
  8. ↑ Ernest H. Nickel , Monte C. Nichols: IMA / CNMNC List of Minerals 2009. (PDF; 1.82 MB) In: cnmnc.main.jp. IMA / CNMNC, January 2009, accessed August 26, 2020 .
  9. ↑ List of locations for Annabergit in the Mineralienatlas and Mindat , accessed on August 26, 2020.
  10. ↑ Petr Korbel, Milan Novák: Mineral Encyclopedia (=  Dörfler Natur ). Edition Dörfler im Nebel-Verlag, Eggolsheim 2002, ISBN 978-3-89555-076-8 , p. 178 .