Whewellite
- Calcium oxalate
- Oxalsauerer lime
D ( calc. ) = 2:22
Whewellite is a rarely occurring mineral from the mineral class of " organic compounds ". It crystallizes in the monoclinic crystal system with the chemical composition Ca ( C2O4 ) · H2O, is so chemically seen a calcium oxalate.
Whewellite usually develops colorless and transparent crystals up to 20 cm Size of isometric to short prismatic habit, but also heart-shaped twins. In polycrystalline training in massive aggregates Whewellite can look white and accept by foreign admixtures also a gray, yellowish or brownish color. The stroke color of the mineral, however, is always white.
Etymology and history
Whewellite was first discovered in the " Good luck slot " in Burgk ( Freital ) in Saxony and described in 1852 by Henry James Brooke ( 1771-1857 ) and William Hallowes Miller ( 1801-1880 ), which is the mineral after the British philosopher and historian of science William Whewell (1794-1866) listed.
Classification
In the now outdated but still in use 8th edition of the mineral classification by Strunz the Whewellite belonged to the mineral class of " organic compounds " and then to the Department of " salts of organic acids ", where he, along with Caoxit, Coskrenit - (Ce), Glushinskit Humboldtin, Levinsonit - (Y), Lindbergite, Minguzzit, Moolooit, Natroxalat, Novgorodovait, Oxammit, Stepanovit, Weddellit, Wheatleyit, Zhemchuzhnikovit and Zugshunstit - (Ce), the independent " group of oxalates " was formed.
The 9th edition valid since 2001 and of the International Mineralogical Association (IMA ) used the Strunz'schen Mineral classification assigns the Whewellite also in the category of " organic compounds " and there in the department of " salts of organic acids " a. This division, however, is further subdivided by the type of salt-forming acid, so that the mineral is found according to its composition in the subsection " oxalates ", where it forms the unnamed group 10.AB.45 the only member.
The classification of minerals according to Dana assigns the Whewellite into the class of " Organic Minerals " and then in the same department. Here he is the only member of the unnamed group to find 50.01.01 within the subdivision " salts of organic acids ( oxalates ) ".
Education and Locations
Even if it is the salt of an organic acid at Whewellite, they must be involved in the formation of no biological processes. Whewellite forms as rarely occurring primary mineral in low grade hydrothermal carbonate - sulphide veins or geodes. Accompanying minerals include calcite, barite, sphalerite, pyrite, Weddellit and waxy hydrocarbons.
Worldwide, Whewellite so far (as of 2011) are detected in about 60 localities. Apart from its type locality Burgk the mineral in Germany nor in Freiberg, Schlema and Hartenstein, Saxony could; at Peine in Lower Saxony; at Ibbenbüren in North Rhine-Westphalia; in " Hannebacher Ley " in the Rhineland-Palatinate community Spessart ( Brohltal ) and near Gera in Thuringia. In Austria, Whewellite found previously only on Graukogellift in the Hohe Tauern.
Other localities are located in Australia, Brazil, France, Greenland, Italy, Mexico, Romania, Russia, Slovakia, Czech Republic, Ukraine, Hungary, England in the United Kingdom and in several regions in the United States of America (USA).
Whewellite can crystallize in urine and lead to the formation of urinary stones. Cause is usually a high oxalic acid or Calciumoxalataufnahme with food ( sorrel, spinach, Swiss chard, beets, cocoa). In veterinary medicine Whewellite Stones mainly occur in dogs and cats becoming increasingly common.
Crystal structure
Whewellite crystallizes in the monoclinic space group ( Raumgruppen-Nr. 14) with the lattice parameters a = 6.29 Å; b = 14.58 Å; c = 10.12 Å and β = 109.5 ° and 8 formula units per unit cell.