Iranite

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Iranite
Phoenicochroite, Iranite-235291.jpg
Small, light brown Iranite crystals on dark pink Phoenicochroit
General and classification
other names

Khuniit (obsolete)

chemical formula Pb 10 Cu (CrO 4 ) 6 (SiO 4 ) 2 (OH) 2
Mineral class
(and possibly department) 		Silicates and Germanates
System no. to Strunz
and to Dana 		7.FC.15 ( 8th edition : VIII / B.28-010)
36.01.01.01
Crystallographic Data
Crystal system Triclinic
Crystal class ; symbol triklin-pedial, 1
Space group P 1 (No. 1)Template: room group / 1
Lattice parameters a  = 9.57  Å ; b  = 11.42 Å; c  = 10.84 Å,
α  = 120.23 °; β  = 92.27 °; γ  = 56.6 °
Formula units Z  = 1
Frequent crystal faces { 1 00}, {010}, {011}, { 1 0 1 }, {00 1 }, {102}
Twinning to {12 1 }
Physical Properties
Mohs hardness not defined
Density (g / cm 3 ) calculated: 5.8
Cleavage Please complete!
colour brown to orange
Line color Saffron yellow
transparency Please complete!
shine Resin gloss
Crystal optics
Refractive indices n α  = 2.25 to 2.30
n β  = not defined
n γ  = 2.40 to 2.50
Optical character Biaxial
Axis angle 2V = very large
Other properties
Chemical behavior soluble in warm sodium carbonate solutions

Iranite is a very rare mineral from the mineral class of silicates and germanates . It crystallizes in the triclinic crystal system with the chemical composition Pb 10 Cu (CrO 4 ) 6 (SiO 4 ) 2 (OH) 2 . It contains silicate groups as well as chromate groups and hydroxide groups , plus the metals lead and copper . In one of the mineral samples examined, fluorine was found in addition to the hydroxides .

The crystals of Iranite are up to 1 mm in size and are uneven.

Etymology and history

The mineral was first described by P. Bariand and P. Herpin in 1963. They named it after Iran , the type locality of the new mineral. In American Mineralogist published Michael Fleischer out as in AM usual, a brief description, using the results of Bariand and Herpin. In it he recorded the formula PbCrO 4 · H 2 O. This finding had to be revised: In 1967 Michael Fleischer published in AM that a new analysis had discovered copper and - in traces - tin in the type material . Khuniite , which had been described in between, was also assigned to the Iranite. Iranite was described here as a copper analogue to hemihedrite . In the meantime, the above applies. Molecular formula Pb 10 Cu (CrO 4 ) 6 (SiO 4 ) 2 (OH) 2 .

classification

Already in the outdated, but partly still in use 8th edition of the mineral systematics according to Strunz , the Iranite belonged to the mineral class of "silicates and germanates" and there to the department of "island silicates with non-tetrahedral anions (Neso-subsilicates)", where together with hemihedrite, Macquartit and Wherryite formed an unnamed group with the system number VIII / B.28.

The 9th edition of Strunz's mineral systematics , which has been in force since 2001 and is used by the International Mineralogical Association (IMA), assigns Iranite - also in the mineral class of "silicates and germanates" - to the "chromates" department. However, this is further subdivided according to the other anions involved , so that the mineral can be found according to its composition in the sub-section "With PO 4 , AsO 4 , SiO 4 ", where together with hemihedrite the "Iranite group" named after it can be found forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , has its own mineral class for chromates, the collective class "sulfates, chromates and molybdates", which in the Strunz system was limited to "sulfides and sulfosalts". Here the Iranite forms the unnamed group 36.01.01 within the group of “chromates” in the subgroup of “compound chromates with different formulas” , also together with hemihedrite.

Crystal structure

Iranite crystallizes triclinic in the space group P 1 (space group No. 1) with the lattice parameters a  = 7.89  Å , b  = 7.84 Å, c  = 11.01 Å, α  = 120.23 °, β  = 92, 27 ° and γ  = 56.6 ° and one formula unit per unit cell . Template: room group / 1

properties

Iranit is easily soluble in warm sodium carbonate solutions.

Education and Locations

Iranite (brown, leafy crystals) with wulfenite (red, superimposed crystals) from the Santa Ana Mine, Tocopilla , Antofagasta, Chile (size: 2.3 cm × 2.1 cm × 1.7 cm)

Since Iranite is a rare mineral formation, there are only a few sites. The type locality is in the "Sebarz Mine" in Anarak near Nain , Isfahan , Iran. In addition, Iranite can also be found in the “Chah Khouni Mine”, also in Anarak. Also in Chile in the Región de Antofagasta there are Iranite at a total of three sites. Most of the sites are found in the United States of America . They are located in Arizona , Colorado , Nevada, and New Mexico .

See also

literature

  • P. Bariand and P. Herpin: Une nouvelle espèce minérale: l'iranite, chromaté hydrate de plomb . In: Bulletin de la Société Française de Minéralogie et de Cristallographie . Vol. 86, 1963, pp. 133-135 ( PDF ).
  • D. Adib, J. Ottermann, B. Nuber: Further data on khuniite [iranite-hemihedrite] from the Tschah Khuni mine, Anarak, Iran . In: New Yearbook of Mineralogy, monthly books . 1972, p. 328-335 .
  • P. Bariand, JF Poullen: Rare chromates from Seh-Changi, Iran . In: The Mineralogical Record . Vol. 11, 1980, pp. 293-297 .

Web links

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

Individual evidence

  1. ↑ a b c IMA / CNMNC List of Mineral Names; December 2014 (English, PDF 1.5 MB)
  2. ↑ a b c Iranite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 59.7 kB )
  3. ↑ a b Iranite near Mindat (English)
  4. ↑ Michael Fleischer: New Mineral Names . In: American Mineralogist . tape 48 , 1963, pp. 1413-1421 ( PDF ). Iranite on page 1417
  5. ↑ Michael Fleischer, Adolf Pabst, JA Mandarino, George Y. Chao, Louis J. Cabri: New Mineral Names . In: American Mineralogist . tape 61 , 1976, p. 174-186 ( PDF ). Iranit on page 186
  6. ↑ Mineral Atlas: Iranit