Hidalgoite
Hidalgoite is a rarely occurring mineral from the mineral class of " phosphates, arsenates and vanadates ." It crystallizes in the trigonal crystal system with the chemical composition PbAl3 [( OH) 6 | SO4 | AsO4 ], so it is a lead -aluminum sulphate - arsenate with additional hydroxide ions.
Hidalgoite is found predominantly in the form of granular to compact, porcelain or porous mass and crack fillings. Even small, spherulitic or low one mineral aggregates are known. Very rarely develops Hidalgoite microscopically small crystals with scalenohedral habit. In its pure form Hidalgoite is colorless and transparent. However, he is due to its polycrystalline training usually translucent white or takes by foreign admixtures a light green, pistachio green or emerald green color.
Etymology and history
Was first discovered Hidalgoite in the " San Pascual Mine" at Zimapán (Municipio Zimapán ) in the Mexican state of Hidalgo and described in 1953 by Robert L. Smith, Frank S. Simons and Angelina C. Vlisidis that the mineral is named after the state in which its type locality is located.
The type material of the mineral is in the Mines ParisTech ( École des Mines de Paris) in France and Harvard University in Cambridge, Massachusetts ( Katelog-Nr. 106373-106375 ) and the National Museum of Natural History in Washington, DC (Catalog No. 112726, 112727 ) preserved in the United States.
Classification
In the outdated, but partly still in use 8th edition of the mineral classification by Strunz the Hidalgoite belonged to the mineral class of " phosphates, arsenates and vanadates " and then to the Department of " water clear phosphates, with foreign anions F, Cl, O, OH ", where he along with Beudantite, Corkite, Gallobeudantit, Hinsdalite, Kemmlitzit, Orpheit, Schlossmacherit, Svanbergit and Woodhouseit the " Beudantite group " 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 Hidalgoite 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 other anions (OH, etc. ) to the phosphate, arsenate or vanadate complex ( RO 4 ), so that the mineral according to its composition in the subdivision " with medium -sized and large cations, (OH, etc.): RO 4 = 3 " is to find where it together with Beudantite, Corkite, Gallobeudantit, Hinsdalite, Kemmlitzit, Orpheit, Svanbergit, Weilerit and Woodhouseit 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 Hidalgoite in the class of " phosphates, arsenates and vanadates " and there in the department of " phosphates " one. Here he is as also in the " Beudantitgruppe " with the system no. Find 43.04.01 within the subdivision " Composite phosphates, etc., ( composite Anhydrous anions with hydroxyl or halogen) ".
Education and Locations
Hidalgoite formed secondarily in the oxidation zone of polymetallic sulphide deposits. Accompanying minerals among other Beudantite, Carbonatcyanotrichit, limonite, Mansfieldit and various tourmalines may occur.
A rare mineral formation Hidalgoite could be detected only in a few localities, where so far (as of 2014) are about 60 localities known as. Its type locality " San Pascual Mine" in Hidalgo is the only known locality in Mexico.
In Germany Hidalgoite could, among other things in the pit " Michael" at the hamlet and the Pit " Silbereckle " at Reichenbach ( Lahr ) in the Black Forest in Baden- Württemberg; at Gadernheim and at Gray Stone at Wiesbaden- wife rock in Hesse; in the antimony mine Caspari at Uentrop ( Arnsberg ), in Ramsbeck, in the quarry Plöger in Velbert, the pit United Gluckauf at Rösrath and " Genna zinc smelter " in Letmathe in North Rhine-Westphalia; in the pit Friedrichssegen in Bad Ems / Lahnstein in Rhineland -Palatinate and the Pit " Sauberg " in honor Friedersdorf in Saxony.
In Switzerland, you know the mineral so far only from the Mürtschenalp in the Murg Valley (Val Murg ), Canton of Glarus.
Other localities lie including Australia, Belgium, Chile, China, France, Greece, Ireland, Italy, Japan, Namibia, Portugal, Spain, Sweden, the United Kingdom ( UK) and the United States of America (USA).
Crystal structure
Hidalgoite trigonal crystallized in the space group R3m ( Raumgruppen-Nr. 166) with the lattice parameters a = 7.04 Å and c = 16.99 Å and three formula units per unit cell.