Jarosite is both an individual mineral and a collective name for many minerals that are related. It is a potassium and iron simple hydrous sulfate with a chemical formula of KFe3+3(OH)6(SO4)2. Jarosite is the group’s most frequent member; Ammoniojarosite, Argentojarosite, Beaverite, Dorallcharite, Hydroniumjarosite, Natrojarosite, and Plumbojarosite are some of the other rare members. In ore deposits, this sulfate mineral is formed by the oxidation of iron sulfides. During the purification and processing of zinc, Jarosite is often produced as a byproduct and is often commonly associated with acid mine drainage and soil environments of acid sulfate.
The German mineralogist August Breithaupt first described Jarosite in 1852 in the Barranco Jaroso type locality in the Sierra Almagrera region of southern Spain. With basal cleavage, a hardness of 2.5-3.5, and a specific gravity of 3.15-3.26, it has a trigonal crystal structure and is brittle. The exploration rover Opportunity on Mars was observed in 2004 by Jarosite, suggesting the possible existence of water that once existed on Mars.
With a vitreous to dull luster, Jarosite is translucent to opaque and is dark yellow to yellowish-brown in hue. It may also be confused with the limonite or goethite with which the gossan (oxidized cap over an ore body) normally occurs. Jarosite is a potassium aluminum sulfate, alunite, and an iron analogue.
Jarosite is not a mineral that is commercial in importance. It is common among micro mount collectors, however, who find this mineral interesting in shape and color, which is only in small crystals. The mineral is the same color as the herb. Under the Temple of the Feathered Serpent, an ancient six-level stepped pyramid 30 miles from Mexico City, enigmatic spheres of clay 1.5 to 5 inches in diameter and coated with jarosite have been discovered.
Jarosite is a mineral that is not normal. Three Martian rovers, Curiosity, Spirit, and Opportunity, have identified ferric sulfate and jarosite. These compounds are representative of the predominant highly oxidizing conditions on the surface of Mars. In the Jaroso Ravine in Sierra Almagrera, Spain, Jarosite was discovered and the type of locality for which it was named. In Spain, it is also located at the La Murta mine in Castellon. Caldbeck Fells, Cumbria, England; the Clara Mine in Rankach, Baden-Württemberg, Germany; Huanani, Bolivia; and Sierra Pena Blanca, Chihuahua, Mexico are other European localities for Jarosite.
Crystal structure of Jarosite (mineral)
Jarosite is not a mineral that is commercial in importance. It is common among micro mount collectors, however, who find this mineral interesting in shape and color, which is only in small crystals. Jarosite is also a more common term that denotes a large family of type compounds, AM3(OH)6(SO4)2, where A+ = Na, K, Rb, NH4, H3O, Ag, Tl, and M3+ = Fe, Cr, V. It is easily recognized by Jarosite’s crystal forms combined with its color. However, it can be hard to differentiate poorly crystallized examples and large forms of Jarosite from other minerals, such as Limonite. Jarosite is also indistinguishable by ordinary methods from its isomorphous mineral Natrojarosite.