Bruggenite

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Bruggenite
General and classification
other names

IMA1970-040

chemical formula Ca (IO 3 ) 2  · H 2 O
Mineral class
(and possibly department) 		Oxides and hydroxides
System no. to Strunz
and to Dana 		4.KC.10 ( 8th edition : IV / L.01)
01/21/02/01
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic; 2 / m
Room group (no.) P 2 1 / c (No. 14)
Lattice parameters a  = 8.50  Å ; b  = 10.00 Å; c  = 7.50 Å
β  = 95.2 °
Formula units Z  = 4
Frequent crystal faces {010}, {011}
Physical Properties
Mohs hardness 3.5
Density (g / cm 3 ) measured: 4.24 (1); calculated: 4.244
Cleavage not known
Break ; Tenacity clamshell; brittle
colour colorless to light yellow
Line color White
transparency transparent to translucent
shine Glass gloss
Crystal optics
Refractive indices n α  = 1.776
n β  = 1.799
n γ  = 1.821
Birefringence δ = 0.045
Optical character biaxial negative
Axis angle 2V = 86 to 96 ° (measured); 86 ° (calculated)

Bruggenite is a very rare mineral from the mineral class of " oxides and hydroxides ". It crystallizes in the monoclinic crystal system with the composition Ca (IO 3 ) 2  · H 2 O, so from a chemical point of view it is a water-containing calcium iodate , i.e. a salt of iodic acid .

In its pure form, Brüggenite is colorless and transparent. However, due to multiple refraction due to lattice construction defects or polycrystalline design, it can also appear white and, due to foreign admixtures, take on a light yellow color, the transparency decreasing accordingly.

Special properties

Bruggenite is generally water-soluble, dissolving quickly in hot water, but only slowly in cold water. Like all iodates , Brüggenit is a strong oxidizing agent and therefore not very stable as a mineral.

Etymology and history

Bruggenite was first discovered in the Pampa del Pique III in the Chilean Región de Antofagasta and described in 1971 by George Edward Ericksen (1920–1996), ME Mrose and JW Marinenko, who named the mineral after Juan Brüggen (1887–1953). Brüggen was a professor at the Universidad de Chile and wrote the first textbook on the geology of Chile ( Fundamentos de la Geologia de Chile , 1950).

Type material of the mineral was deposited in the National Museum of Natural History in Washington DC (register no. 122445).

classification

In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , Brüggenit belonged to the mineral class of "oxides and hydroxides" and there to the department of "iodates" ( iodates ), where together with Dietzeit and Lautarit it belonged to the unnamed group IV / L .01 made.

The 9th edition of Strunz's mineral systematics, which has been in force since 2001 and is used by the International Mineralogical Association (IMA), also assigns Bruggenite to the class of “oxides and hydroxides” and there to the “iodates” division. However, this section is further subdivided according to the possible presence of further anions and water of crystallization in the compound, so that the mineral according to its composition in the sub-section “Iodates without additional anions; with H 2 O “is to be found, where it is the only member of the unnamed group 4.KC.10 .

In contrast to the Strunz systematics, the systematics of minerals according to Dana , which is mainly used in the English-speaking world, assigns Bruggenite to the class of " carbonates , nitrates and borates " and there in the section of "iodates - anhydrous and hydrous". Here he is to be found as the only member of the unnamed group 01/21/02 within the sub-section “ Iodates - anhydrous and water-containing with different formulas ”.

Education and Locations

Brüggenit found along with niter as crack filling ( impregnation ) in decomposed rhyolite - tuffs . In addition to nitronatrite, anhydrite , lautarite , hydroboracite and halite can also occur as accompanying minerals .

In addition to the type locality Pampa del Pique III, so far (as of 2012) only Zapiga in the province of Iquique ( Región de Tarapacá ), which is also in Chile, is known as another location for Bruggenite.

Crystal structure

Brüggenite crystallizes monoclinically in the space group P 2 1 / c (space group no. 14) with the lattice parameters a  = 8.50  Å ; b  = 10.00 Å; c  = 7.50 Å and β = 95.2 ° and 4 formula units per unit cell .

See also

literature

Web links

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.  283 .
  2. ↑ Webmineral - Brüggenite
  3. ↑ a b c d John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols: Brüggenite , in: Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 65.8 kB )
  4. ↑ a b c d Mindat - Brüggenite
  5. ↑ Howard T. Evans, jr .: Memorial of George E. Ericksen 1920-1996 , in: American Mineralogist , Volume 82 (1997), pp. 1046-1048 PDF 55.4 kB