Jarosite: The mineral jarosite information and pictures

About

Jarosite is both an individual mineral, as well a group name of several similar minerals. Jarosite is the most common member of the group; some of the other rare members include Ammoniojarosite, Argentojarosite, Beaverite, Dorallcharite, Hydroniumjarosite, Natrojarosite, and Plumbojarosite.
Jarosite was first described in 1852 by German mineralogist August Breithaupt in type locality of Barranco Jaroso in the Sierra Almagrera in Southern Spain. In 2004, it was detected by the exploration rover Opportunity on Mars, indicating the possible presence of water that once existed on Mars.

Crystal Forms & Aggregates

Generally only is small crystals, which are hexagonal or triangular shaped, and may also be tabular or pseudocubic. Also drusy, grainy, as fibrous crusts, in nodules, and in thin, hexagonal scales.

Striking Features

Crystal habits and color

Environment

Forms through weathering in arid regions as a secondary mineral.

Uses

Jarosite is not an industrially important mineral. However, it is popular among micromount collectors who find this mineral, which is only in small crystals, interesting in shape and color.

Noteworthy Localities

Jarosite is not a common mineral. It has been found in the Jaroso Ravine in Sierra Almagrera, Spain, the type locality for which it was named after. It is also found in Spain in the La Murta Mine, Castellon. Other European localities for Jarosite are Caldbeck Fells, Cumbria, England; the Clara mine in Rankach, Baden-Wurttemberg, Germany; Huanani, Bolivia; and Sierra Pena Blanca, Chihuahua, Mexico.

In the U.S., Jarosite exists in several localities in Nevada, specifically at the Silver Coin Mine, Valmy, Humboldt Co.; Majuba Hill, Pershing Co.; and the Gilbert District, Goldfield, Esmeralda Co. Other occurrences are Bisbee and Tombstone, Cochise Co., Arizona; the Tintic District, Juab Co., Utah; the Iron Arrow Mine, Chaffee Co., Colorado; and Girard, Burke Co., Georgia. An important Mexican locality for Jarosite is Sierra Peña Blanca, Chihuahua.

Common Mineral Associations

Pyrite, Galena, Hematite, Barite, Variscite, Turquoise

Distinguishing Similar Minerals

Jarosite's crystal forms combined with its color easily identify it. However, poorly crystallized examples and massive forms of Jarosite may be difficult to distinguish from other minerals, such as Limonite. Jarosite is also indistinguishable from its isomorphous mineral Natrojarosite by ordinary methods.