Hydrozincite

from Wikipedia, the free encyclopedia
Hydrozincite
Hydrozincite (zinc blossom) - Bleiberg, Kärnten.jpg
Hydrozincite (zinc bloom) from Bleiberg in Carinthia
General and classification
other names
  • Zinc bloom
  • Marionite
chemical formula Zn 5 [(OH) 6 | (CO 3 ) 2 ]
Mineral class
(and possibly department) 		Carbonates (and relatives)
System no. to Strunz
and to Dana 		5.BA.15 ( 8th edition : V / C.01)
16a.04.01.01
Similar minerals Calcite, aragonite
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic; 2 / m
Room group (no.) C 2 / m (No. 12)
Lattice parameters a  = 13.62  Å ; b  = 6.30 Å; c  = 5.42 Å
β  = 95.8 °
Formula units Z  = 2
Twinning Contact twins after {100}
Physical Properties
Mohs hardness 2 to 2.5
Density (g / cm 3 ) 4th
Cleavage completely after {100}
Break ; Tenacity shell-like
colour colorless, white, gray, yellowish, brown, pink, green
Line color White
transparency transparent to opaque
shine Pearl luster, silk luster, matt or earthy in massive aggregates
Crystal optics
Refractive indices n α  = 1.630
n β  = 1.642
n γ  = 1.750
Birefringence δ = 0.120
Optical character biaxial negative
Axis angle 2V = 40 °
Other properties
Chemical behavior Soluble in acids with release of CO 2

Hydrozincite , also known under the mining name zinc blossom or the outdated synonym marionite , is a rather seldom occurring mineral from the mineral class of " carbonates (and relatives)". It crystallizes in the monoclinic crystal system with the chemical composition Zn 5 [(OH) 6 | (CO 3 ) 2 ] and develops mostly opaque white, earthy or massive mineral aggregates , but rarely transparent, colorless to white-yellow, tabular crystals in the millimeter range. Occasionally, bluish or pink aggregates occur due to foreign admixtures.

Special properties

Hydrozincite and zincite under normal and UV light

Occasionally, hydrozincite shows bluish fluorescence under UV light .

Hydrozincite is infusible in front of the soldering tube.

Etymology and history

Hydrozincite was first found in 1853 near Bad Bleiberg in the Villach-Land district in Austria and described by Gustav Adolf Kenngott , who described the mineral in terms of its chemical composition, which contains zinc and hydroxide ions .

Based on its crystallization form, which often occurs in the form of crusty coatings or efflorescence, the mineral received its mining designation zinc blossom .

classification

In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the hydrozincite still belonged to the common mineral class of "carbonates, nitrates and borates " and there to the department of "C. Anhydrous carbonates with foreign anions ", where together with aurichalcite , azurite , brianyoungite , georgeit , glaucomaite , kolwezite , losyite , mcguinnessite , malachite , nullaginite , pokrovskite , rosasite , sclarite and zinc rosasite , the" azurite-rosasite series " No. V / C.01 formed.

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 the hydrozincite to the “Carbonates with additional anions; without H 2 O “. However, this is now more precisely subdivided according to the cations involved , so that the mineral can be found according to its composition in the sub-section “With Cu, Co, Ni, Zn, Mg, Mn”, where together with aurichalcite he named those after the two minerals Group with the system no. 5.BA.15 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the hydrozincite to the section “Carbonates - Hydroxyl or Halogen” and there in the sub-section “ Carbonates - Hydroxyl or Halogen” with the general formula (AB) 5 (XO 3 ) 2 Z q “, where he can be found as the only member in the unnamed group 16a.4.1 .

Education and Locations

Calcite scalenohedron overgrown with hydrozincite on a crystal lawn of red sphalerite

Hydrozincite is formed in the oxidation zones of zinc deposits as masses or crusts. Crystals are rarely found. Hydrozincite, although present on many mineral specimens, is ignored or is often confused with a more common mineral such as calcite or aragonite. Accompanying minerals include aurichalcite, calcite , cerussite , hemimorphite , smithsonite , sphalerite , willemite and limonite .

Hydrozincite has so far (as of 2010) been detected at around 725 sites worldwide, including Egypt , Algeria , Australia , Belgium , Bolivia , Brazil , Bulgaria , Chile , China , Germany , France , Greece , Guatemala , India , Iran , Ireland , Isle of Man , Italy , Japan , Canada , Democratic Republic of the Congo , Madagascar , Mexico , Namibia , Norway , Austria , Poland , Portugal , Romania , Russia , Zambia , Sweden , Switzerland , Slovakia , Slovenia , Spain , South Africa , Czech Republic , Tunisia , Turkey , Hungary , the United Kingdom (Great Britain), the United States of America (USA) and Vietnam .

Crystal structure

Hydrozincite crystallizes monoclinically in the space group C 2 / m (space group no. 12) with the lattice parameters a  = 13.62  Å ; b  = 6.30 Å; c  = 5.42 Å and β = 95.8 ° as well as 2 formula units per unit cell .

use

Hydrozincite can contain up to 60% zinc, but economical mining is only worthwhile if the mineral accumulates locally.

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 , p. 294 .
  2. ↑ a b Webmineral - Hydrozincite (English)
  3. ↑ a b c Hydrozincite at mindat.org (engl.)
  4. ↑ Old mineral names and synonyms - Marionite (PDF 2.6 MB; p. 111)
  5. ↑ Mindat - Localities for Hydrozincite

literature

Web links

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