Devilline

Devillin, also known as Devillit, Herrengrundit, Lyellit or Úrvölgyit, is a rarely occurring mineral from the mineral class of " sulfates ( and Related ) ". It crystallizes in the monoclinic crystal system with the chemical composition Cu4Ca [( OH) 6 | (SO4 ) 2] • 3H2O and usually develops needle-like or dünntafelige crystals with pseudohexagonalem habit in rosette -like or tufted mineral aggregates, but also crusty coating of blue-green, dark emerald green to patina green color with light green stroke color.

The uninjured surfaces of transparent to translucent crystals have a glass- like sheen on cleavage surfaces, however, more pearlescent. With a Mohs hardness of about 2.5 between the reference Devillin mineral gypsum ( 2 ), and calcite (3).

Etymology and history

Was first discovered in the English county of Cornwall Devillin and described in 1864 by MF Pisani, who named the mineral after the French chemist Henri Étienne Sainte -Claire Deville ( 1818-1881 ).

Its synonyms Herrengrundit and Úrvölgyit received Devillin due to rich mineral discoveries and descriptions of the Slovak region Špania Dolina to German " Mr. Basic " or Hungarian " Úrvölgy ".

Classification

In the now outdated but still in use 8th edition of the mineral classification by Strunz the Devillin to the mineral class of " sulfates, selenates, tellurates, chromates, molybdates and tungstates " belonged and there to the Department of " water -containing sulfates with foreign anions ", where he with Arzrunit, Campigliait, Lautenthalit, Niedermayrit, Orthoserpierit, Serpierite and Tatarskit formed a distinct group.

The 9th edition used since 2001 and valid by the International Mineralogical Association (IMA ) of the Strunz'schen Mineral classification assigns the Devillin also in the class of " sulfates ( selenates, tellurates, chromates, molybdates and tungstates ) " and then in the Department of " Sulfate ( selenates, etc.) with additional anions, with H2O" one. This division, however, is further divided according to the size of the involved cations and the crystal structure, so that the mineral according to its composition in the subdivision " with medium-sized cations; Layers of edge-sharing octahedra, " is to find where it forms the unnamed group 7.DD.30 together with Campigliait, Lautenthalit, Niedermayrit, Orthoserpierit and Serpierite.

The mostly commonly used in English-speaking classification of minerals according to Dana assigns the Devillin in the class of " sulfates, chromates and molybdates " and there in the department of " Hydrous sulfates with hydroxyl or halogen" one. Here he is with Lautenthalit in the unnamed group 06.31.01 within the sub-division of " water -containing sulfates with hydroxyl or halogen with (A B2 ) 5 ( XO4 ) 2ZQ × x (H2O) " to find.

Education and Locations

Devillin is a secondary mineral that is present in the oxidation zone of copper sulfides. Because it is formed by oxidation with atmospheric oxygen, it can also be formed on Halden as a secondary mineral. Accompanying minerals include Antlerite, azurite, Brochantite, gypsum, Langit, Linarit, malachite and Posnjakit.

Devillin is one of the rarely occurring minerals, so can be in different localities partly abundant, but overall is not widespread. So far (as of 2011) were registered around 300 localities. Apart from its type locality, the mineral Cornwall in the United Kingdom (Great Britain ) occurred yet in the regions of Cumbria, Devon, Shropshire and Staffordshire in England; at Wanlockhead on in Scotland and the Welsh regions Ceredigion, Gwynedd and Powys.

Noteworthy due to exceptional Devillinfunde is amongst the region Špania Dolina ( Herrengrund, Úrvölgy ) in Slovakia, coming out of the best ever examples of crystal rosettes with a diameter of up to one centimeter.

In Germany Devillin found so far mainly in the Black Forest in Baden- Württemberg, in the Bavarian Fichtelgebirge and the Upper Palatinate Forest, near Frankfurt, and Richelsdorf in Hesse, in the Harz Mountains of Lower Saxony to Saxony- Anhalt, in the low Bergisch Land, Sauerland and winners district of North Rhine -Westphalia, in the Eifel and the Lahn Valley, the Hunsrück, in Imsbach and by Rhine Breitbach in Rhineland- Palatinate, in the Ore Mountains and the Upper Lusatia in Saxony, on Heligoland Schleswig -Holstein and in Greiz, Ilfeld and the former Absetzerhalde at Ronneburg in Thuringia.

Even in rock samples from the Mid-Atlantic Ridge Devillin could be detected.

Other localities lie including Belgium, Canada, Chile, France, Greece, Ireland, Italy, Japan, Kazakhstan, the Democratic Republic of Congo, Morocco, Mexico, Namibia, New Zealand, Norway, Austria, Poland, Portugal, Sweden, Switzerland, Spain, Czech Republic, Hungary and the United States of America (USA).

Crystal structure

Devillin crystallizes in the monoclinic space group P21 / c ( Raumgruppen-Nr. 14) with the lattice parameters a = 20.87 Å; b = 6.14 Å; c = 22.19 Å and β = 102.7 °, and eight formula units per unit cell.

Devillin is a mineral with a strong anisotropy, which means that its properties are different in the three main axes.