Callaghanite
| Callaghanite | |
|---|---|
 |
|
| General and classification | |
| chemical formula | Cu 2 Mg 2 [(OH) 6 | CO 3 ] • 2H 2 O |
|
Mineral class (and possibly department) |
Carbonates and nitrates |
|
System no. to Strunz and to Dana |
5.DA.25 ( 8th edition : V / E.07) 16b.05.01.01 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Room group (no.) | C 2 / c (No. 15) |
| Lattice parameters |
a = 10.1 Å ; b = 11.75 Å; c = 8.21 Å β = 107.4 ° |
| Formula units | Z = 4 |
| Frequent crystal faces | {111}, {11 1 }, {122}, {12 2 } |
| Physical Properties | |
| Mohs hardness | 3 to 3.5 |
| Density (g / cm 3 ) | measured: 2.71; calculated: 2.65 |
| Cleavage | completely according to {111} and {11 1 } |
| Break ; Tenacity | uneven; brittle |
| colour | azure blue to blue violet |
| Line color | White |
| transparency | transparent to translucent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.559 n β = 1.653 n γ = 1.680 |
| Birefringence | δ = 0.121 |
| Optical character | biaxial negative |
| Axis angle | 2V = measured: 55 °; calculated: 52 ° |
Callaghanite is a very rarely occurring mineral from the mineral class of "carbonates and nitrates". It crystallizes in the monoclinic crystal system with the chemical composition of Cu 2 Mg 2 [(OH) 6 | CO 3 ] · 2H 2 O and is therefore chemically seen a hydrous copper - magnesium - carbonate with additional hydroxide .
Callaghanite only develops small, dipyramidal, pseudo- octahedral crystals up to about 0.3 millimeters in size and is usually found in the form of crusty coatings or massive mineral aggregates in rock veins. The transparent to translucent crystals are azure to blue-violet in color and have a glass-like sheen on the surface . However, Callaghanit leaves a white line on the whiteboard .
Special properties
Callaghanite dissolves slowly and foams in dilute hydrochloric acid (HCl).
Etymology and history
Callaghanite was first discovered in the "Premier Chemicals Mine" ( Basic Refractories Mine , Gabbs Magnesite-Brucite Mine ) near Gabbs in Nye County , Nevada, and described in 1954 by Carl W. Beck and John H. Burns, who used the mineral the director of the "New Mexico Bureau of Mines and Minerals" Dr. Eugene Callaghan named to honor his geological work on magnesite deposits.
Type material of the mineral is kept in the National Museum of Natural History in Washington, DC, USA (Catalog No. R9406).
classification
In the outdated, but partly still in use, 8th edition of the mineral classification according to Strunz , the callaghanite belonged to the common mineral class of "carbonates, nitrates and borates" and there to the department of "hydrous carbonates with foreign anions ", where together with claraite and decrespignyite (Y) formed the unnamed group V / E.07 .
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), assigns callaghanite to the newly defined class of "carbonates and nitrates" (the borates form a separate class here), but also in the department of “carbonates with additional anions; with H 2 O “. This is, however, further subdivided according to the relative size of the cations involved , so that the mineral can be found according to its composition in the sub-section “With medium-sized cations”, where it is the only member of the unnamed group 5.DA.25 .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns callaghanite to the common class of "carbonates, nitrates and borates" and there in the category of "carbonates with hydroxyl or halogen" like the outdated Strunz system. Here he is the only member of the unnamed group 16b.05.01 within the sub-section “ Carbonates - Hydroxyl or Halogen with Different Formulas ”.
Education and Locations
Callaghanite forms in the contact zone between diorite and serpentine dolomite rock , where it occurs in paragenesis with brucite , dolomite , forsterite , magnesite and various serpentines .
As a very rare mineral formation, Callaghanite could so far (as of 2014) only be detected in a small number of samples from less than 10 sites. In addition to its type locality "Premier Chemicals Mine" near Gabbs in Nevada, the mineral only appeared in the United States in the Eagle Picher Mine near Creta in Jackson County of Oklahoma.
In Germany, callaghanite was found on the slag heaps of the Kochhütte (August-Bebel-Hütte) near Helbra and on the “Lichtloch 25” heap of the former copper and silver works ( God's reward ) and the slag heaps of the copper chamber near Hettstedt in Saxony-Anhalt.
In Austria, the mineral is known from the Lobminggraben near Sankt Stefan ob Leoben in Styria and the slag heaps of the Montanwerke Brixlegg in Tyrol.
Furthermore, Callaghanite could only be discovered in the Italian region of Liguria in the Mt. Ramazzo mine near Borzoli and on the slag heaps near Carpenara in Val Varenna.
Crystal structure
Callaghanite crystallizes monoclinically in the space group C 2 / c (space group no. 15) with the lattice parameters a = 10.1 Å ; b = 11.75 Å; c = 8.21 Å and β = 107.4 ° as well as four formula units per unit cell .
See also
literature
- Carl W. Beck, John H. Burns: Callaghanite, a new mineral. In: American Mineralogist. Volume 39, 1954, pp. 630-635 ( PDF 458.7 kB ).
Web links
- Mineral Atlas: Callaghanite (Wiki)
- Database-of-Raman-spectroscopy - Callaghanite
- American-Mineralogist-Crystal-Structure-Database - Callaghanite
Individual evidence
- ↑ 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. 312 .
- ↑ a b c d Callaghanite. In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( PDF 66.8 kB ).
- ↑ Webmineral - Callaghanite
- ↑ a b c Mindat - Callaghanite
- ^ A b Carl W. Beck, John H. Burns: Callaghanite, a new mineral. In: American Mineralogist. Volume 39, 1954, pp. 630-635 ( PDF 458.7 kB ).
- ↑ Find location list for callaghanite at the Mineralienatlas and at Mindat