Cyanotrichite

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Cyanotrichite
Cyanotrichite-241922.jpg
Cyanotrichite from the “Grand View Mine” in Grand Canyon National Park, Arizona, USA
General and classification
chemical formula Cu 4 Al 2 (SO 4 ) (OH) 12 · 2 H 2 O
Mineral class
(and possibly department) 		Sulphates (selenates etc.) with other anions, with H 2 O
System no. to Strunz
and to Dana 		7.DE.10 ( 8th edition : VI / D.08)
02/31/01/01
Crystallographic Data
Crystal system orthorhombic
Crystal class ; symbol n. d.
Lattice parameters a  = 10.16  Å ; b  = 12.61 Å; c  = 2.90 Å
Formula units Z  = 1
Physical Properties
Mohs hardness 1 to 3
Density (g / cm 3 ) 2.74 to 2.95
Cleavage Please complete!
Break ; Tenacity brittle
colour sky blue, light blue, dark blue
Line color pale blue
transparency translucent
shine silky
Crystal optics
Refractive indices n α  = 1.588
n β  = 1.617
n γ  = 1.655
Birefringence δ = 0.067
Optical character biaxial positive
Axis angle 2V = 82 °
Pleochroism none
Other properties
Chemical behavior soluble in acids

Cyanotrichite (also Lettsomite or copper seed ore ) is a rarely occurring mineral from the mineral class of sulfates . It crystallizes in the orthorhombic crystal system with the chemical composition Cu 4 Al 2 (SO 4 ) (OH) 12  • 2 H 2 O and develops characteristic blue, up to three centimeters long, needle-shaped crystals, which are also often thread-like, radial-rayed tufts or finely crystalline , flaky encrustations form on other minerals.

The mineral, together with camérolaite and carbonate cyanotrichite, forms the cyanotrichite group.

Etymology and history

Copper seed ore, which came from the type locality Moldova Nouă in Romania , was first described in 1808 by Abraham Gottlob Werner . The mineral was given its current name in 1830 by Ernst Friedrich Glocker . This is derived from the Greek κύανος [kúanos] (from myk. “Ku-wa-no”) for “dark metal; Email ”, after Homer also“ Bergblau; Lasurstein “and θρίξ [tʰríx], genitive τρίχος [tríkʰos] for hair.

classification

According to the old systematics of minerals according to Strunz (8th edition) , cyanotrichite belongs to the mineral class of "sulfates, selenates , tellurates , chromates , molybdates and tungstates " and there to the department of " hydrous sulfates with foreign anions ". In the new systematics of minerals according to Strunz (9th edition) , this large class was divided more precisely so that the cyanotrichtite is now in the subdivision of "unclassified sulfates (selenates etc.) with other anions, with H 2 O with medium-sized cations" - unclassified because the exact crystal structure could not yet be determined.

The systematics of minerals according to Dana also assigns the mineral to the class of sulphates and there in the division of "water-containing sulphates with hydroxyl groups or halogens contained ".

Education and Locations

Cyanotrichite forms as a secondary mineral in oxidized parts of copper sulfide deposits. It is with Brochantite , Spangolith , Chalkophyllit , Olivenit , Tyrolit , Parnauit , azurite and malachite associated .

Various locations of cyanotrichite are known. They are located in Austria , France , Germany , Greece , Italy , Great Britain , the United States and Australia , among others .

Crystal structure

Cyanotrichite crystallizes in the orthorhombic crystal system with the lattice parameters a = 10.16  Å , b = 12.61 Å and c = 2.90 Å as well as one formula unit per unit cell . The exact space group is not known.

use

Cyanotrichite is too rare to be used as a raw material. If it is associated with other, more productive copper ores, it is also mined with these. The mineral is sought after by collectors due to its color and shape.

See also

Individual evidence

  1. ↑ a b c Webmineral - Cyanotrichite (engl.)
  2. ↑ a b c mindat.org - Cyanotrichite (Engl.)
  3. ^ Type mineral catalog Germany, Mineralogical and Petrographic Institute of the University of Hamburg
  4. ↑ MinDat - Localities for Cyanotrichite (Eng.)

literature

Web links

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