Jarosite

• Yellow iron ore
• Raimondit

Jarosite (also yellow iron ore or Raimondit ) is a commonly occurring mineral from the mineral class of " sulfates " ( and relatives, see Classification ). It crystallizes in the trigonal crystal system with the composition KFe33 [( OH) 6 | (SO4 ) 2], and is therefore chemically seen a potassium -iron sulfate with additional hydroxide ions.

Jarosite is transparent to translucent and developed tabular, pseudo-cubic crystals. Mostly, however, he finds himself in the form of small, crystalline crusts or fibrous, nieriger, granular, powdery or earthy aggregates of amber- yellow to dark brown in color. Uninjured crystal faces have a glass - to diamond-like luster, fracture surfaces shine contrast resin rather similar.

The mineral looks visually the limonite ( limonite ) is quite similar and is sometimes confused with this, especially as it weathered with time on this.

Special Features

The mineral is strongly pyroelectric, ie reacts with interval -like heating and cooling with the construction of an electric voltage.

Etymology and history

Was first discovered jarosite at Barranco Jaroso in the Sierra Almagrera in the Spanish province of Almería and described in 1852 by August Breithaupt, who named the mineral after its type locality.

Classification

In the now outdated but still in use 8th edition of the mineral classification by Strunz the jarosite to mineral class of " sulfates, chromates, molybdates and tungstates " belonged and there to the Department of " water clear sulfates with foreign anions ", where he, together with alunite Ammonioalunit, Ammoniojarosit, Argentojarosit, Beaverite, Dorallcharit, Huangit, hydronium jarosite, Krivovichevit, Minamiit, natroalunite, natrojarosite, Osarizawait, plumbojarosite and Walthierit the " alunite - group " with the system no. VI/B.11 formed.

The 9th edition used since 2001 and valid by the International Mineralogical Association (IMA ) of the Strunz'schen Mineral classification assigns the jarosite in the class of " sulfates (including selenates, tellurates, chromates, molybdates and tungstates ) " and then also in the Department the " sulfates ( selenates, etc.) with other anions, without H2O" a. However, this is further divided according to the relative size of the cations involved, so that the mineral is found according to its composition in the subsection "With medium -sized and large cations " where it together with alunite Ammonioalunit, Ammoniojarosit, Argentojarosit, Beaverite, Dorallcharit, Huangit, hydronium jarosite, Minamiit, natroalunite, natrojarosite, Osarizawait, plumbojarosite and Walthierit the " alunite - group " with the system no. 7.BC.10 forms.

The mostly commonly used in English-speaking classification of minerals according to Dana assigns the jarosite in the class of " sulfates, chromates and molybdates " and there in the department of " water clear sulfates with hydroxyl or halogen" one. Here he is with Natrojarosite, hydronium jarosite, Ammoniojarosit, Argentojarosit, plumbojarosite, Beaverite and Dorallcharit in the " Alunitgruppe ( jarosite subgroup ) " 2/30/05 within the subdivision " Anhydrous sulfates with hydroxyl or halogen with (AB) 2XO4Zq " to find.

Education and Locations

Jarosite forms as a typical secondary mineral weathering of iron sulfides, mainly pyrite. As an accessory mineral occurs in addition to this, you still Natrojarosite, with which it forms a complete solid solution series. In addition, jarosite also forms pseudomorphs after alunite.

Overall, jarosite has been (as of 2012) detected at over 1800 localities.

In Germany jarosite occurred in many places in the Black Forest in Baden- Württemberg; at Hagendorf ( Waidhaus ) in Bavaria; at Kirschhausen, Richelsdorf, Biebergemünd and Essershausen in Hesse; at Müllingen and several places in the Harz Mountains in Lower Saxony; at Friedland in Mecklenburg- Vorpommern; at several locations in the Sauerland and winner country in North Rhine-Westphalia; in many places the Eifel district of North Rhine -Westphalia Rhineland- Palatinate to; in some places at Saarlouis in Saarland; at the Petersberg near Halle, in Hasserode and Staßfurt in Saxony -Anhalt; in many places in the Saxon Erzgebirge, Upper Lusatia and in Oelsnitz / Vogtl. and in Ronneburg, Neumühle / Elster and wrought am Rennsteig in Thuringia.

In Austria, jarosite, especially in Carinthia ( Friesach - hut mountain, Karavanke Kreuzeckgruppe ), Lower Austria ( Waldviertel ), Salzburg ( Hohe Tauern ) and Styria ( Fischbacher Alps, Stubalpe ), but was also on Pauliberg in Burgenland, the Silberberg, the Gratlspitze and the White Schrofen in Tyrol, found at Eferding and Grein in Upper Austria as well as in Fellimännle ( Silbertal ) in Vorarlberg.

In Switzerland, they found the mineral, especially in the Canton of Valais, but also in Grindelwald in the Canton of Bern and at Bex and Eclépens in the canton of Vaud.

Other localities lie include Afghanistan, Antarctica, Argentina, Armenia, Azerbaijan, Australia, Belgium, Bolivia, Brazil, Bulgaria, Chile, China, Denmark, the Democratic Republic of Congo, Ecuador, Eritrea, Estonia, France, Greece, Iceland, India, Indonesia, Iran, Ireland, Italy, Japan, Kazakhstan, Kyrgyzstan, Colombia, Cuba, Madagascar, Mali, Morocco, Macedonia, Mexico, Mongolia, Namibia, the Netherlands, New Zealand, Norway, Pakistan, Papua New Guinea, Peru, the Philippines, Poland, Portugal, Romania, Russia, Sweden, Slovakia, Spain, South Africa, Taiwan, Czech Republic, Ukraine, Hungary, Uzbekistan, the U.S. Virgin Islands, the United Kingdom ( UK), the United States of America (USA ) and Cyprus.

Even in rock samples from the Mid-Atlantic Ridge and the Juan de Fuca Ridge in the Pacific jarosite was detected.

Jarosite was detected by the space probe "Opportunity" on the surface of the planet Mars in March 2004. Because jarosite on Earth can only be formed with the participation of water, the detection is considered as evidence that liquid water was present on Mars.

Jarosite is also found in large quantities in the soil type Organomarsch, the spread in the Altmarschen eg the German North Sea coast has. When creating a soil profile it shows itself in the form of an intense yellow sprinklings in the subsoil where it fails due to very low pH values ​​and the presence of ferrous sulfate. The mineral is named in the language of the region also Maibolt. The name is based on the freshly plowed field ( May Field ) and the superstitious notion of a leprechaun, which stains the floor yellow. The relationship to the popular belief negative connotations Kobold is obvious: A field being plowed at the Maibolt to the surface, carrying for years scarcely plants and was therefore as poisoned by Earth Spirit.

Crystal structure

Jarosite crystallized trigonal space group R3m ( Raumgruppen-Nr. 166) with the lattice parameters a = 7.30 Å and c = 17.27 Å and 3 formula units per unit cell.

Use

Jarosite has no significant application. The mineral is sometimes used as a yellow earth pigment in painting.