Woodhouseite
Woodhouseit is a rarely occurring mineral from the mineral class of " phosphates, arsenates and vanadates ." It crystallizes in the trigonal crystal system with the composition CaAl3 [( OH) 6 | SO4 | PO4 ], and is therefore in chemical terms, a calcium aluminum phosphate with additional sulfate ( [ SO4 ] 2 -) and hydroxide ions (OH - ).
Woodhouseit usually develops rhombohedral, pseudocubic crystals of a few millimeters in size with glass-like sheen on the surfaces (after the c- axis also pearlescent possible). In its pure form it is colorless and transparent. But it may also appear white and accept by foreign admixtures a pink color by multiple refraction due to lattice defects or polycrystalline training, the transparency decreases accordingly.
Etymology and history
Was first discovered Woodhouseit in the "Champion Mine" in the White Mountains in the U.S. state of California, and described in 1937 named by Dwight M. Lemmon, of the mineral after the American mineralogist Charles Douglas Woodhouse ( 1888-1975 ).
Classification
Already in the outdated, but partly still in use 8th edition of the mineral classification by Strunz was one of Woodhouseit to the class' phosphates, arsenates and vanadates "and then to the Department of " water clear phosphates, with foreign anions F, Cl, O, OH " where he collaborated with Beudantite, Corkite, Gallobeudantit, Hidalgoite, Hinsdalite, Kemmlitzit, Orpheit, Schlossmacherit and Svanbergit the " Beudantitgruppe " with the system no. VII/B.35 formed.
The 9th edition valid since 2001 and of the International Mineralogical Association (IMA ) used the Strunz'schen Mineral classification assigns the Woodhouseit also in the department of " phosphates, etc., with additional anions, without H2O" one. However, this is further divided according to the relative size of the involved cations and the molar ratio of the additional union anions (OH, etc. ) to the phosphate, arsenate or Vanadatkomplex ( RO 4 ), so that the mineral according to its composition in the subsection "With medium-sized and large cations, (OH, etc.): RO 4 = 3 " is to find where it together with Beudantite, Corkite, Gallobeudantit, Hidalgoite, Hinsdalite, Kemmlitzit, Orpheit, Schlossmacherit, Svanbergit and Weilerit the" 1 Beudantitgruppe "with the system no. 8.BL.05 forms.
The mainly common in English-speaking classification of minerals according to Dana assigns the Woodhouseit in the class of " phosphates, arsenates and vanadates " and there in the department of " phosphates " one. Here he is with Beudantite, Corkite, Gallobeudantit, Hidalgoite, Hinsdalite, Kemmlitzit, Orpheit, Svanbergit and Weilerit in the unnamed group 43.04.01 within the sub-division of " Composite phosphates, etc. ( Anhydrous composite anions with hydroxyl or halogen) " to find.
Education and Locations
Woodhouseit formed by clayey conversion hydrothermally decomposed, tonmineralreicher rocks such as kaolin, smectite and illite, and can be found either in andalusite Lagerstätteen or in the hydrothermal veins of other mineral deposits. He rarely formed as a transformation product of guano in caves. Accompanying minerals topaz, Augelith, Lazulith and / or pyrophyllite may occur.
A rare mineral formation Woodhouseit could be proven so far only in a few localities, of which approximately 40 localities are known. Apart from its type locality, the "Champion Mine" in the White Mountains of California still entered the mineral in the United States of America ( USA) in some places in Colorado (Boulder County, Conejos County and Rio Grande County), at Graves Mountain in Lincoln County ( Georgia), in the " Algonquin Mine" in Philipsburg ( Montana), in the " Tyrone Mine" in Grant County (New Mexico ) at Skytop near State College in Centre County (Pennsylvania ) and " Willis Mountain Mine " at Farmville in Buckingham County ( Virginia) on.
In Austria, Woodhouseit found so far only at the Little Finagl and on Leutachkopf in Untersulzbachtal.
Other localities lie among others in Argentina, Australia, Belgium, Bolivia, Brazil, Bulgaria, Chile, China, Indonesia, Italy, Japan, Canada, Kyrgyzstan, Norway, Romania, Russia, Spain, Sweden, Hungary and the Czech Republic.
Crystal structure
Woodhouseit trigonal crystallized in the space group R3m ( Raumgruppen-Nr. 166) with the lattice parameters a = 6.99 Å and c = 16.39 Å and three formula units per unit cell.