Jarosite


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jarosite

[jə′rō‚sīt]
(mineralogy)
KFe3(SO4)2(OH)6 An ocher-yellow or brown alunite mineral having rhombohedral crystal structure. Also known as utahite.

Jarosite

 

a mineral of the sulfate class, with chemical composition KFe3(SO4)2(OH)6. Jarosite, which usually contains admixtures of sodium, crystallizes in the trigonal system. It usually occurs in the form of ocher yellow or yellowish brown earthy and fine-grained masses; sometimes it is found in the form of small orthorhombic and pseudoisometric crystals, with a strong vitreous or adamantine luster. It exhibits pyroelectric properties and very high double refraction. It has a hardness of 2.5–3.5 on Mohs’ scale and a density of 3,150–3,260 kg/m3.

Jarosite is formed in the oxidation zone of ore deposits owing to the presence of iron sulfides, such as pyrite and pyrrhotite, mainly under dry climatic conditions. When there is substantial humidity, it decomposes with the formation of iron hydroxides. It is also precipitated from acidic sulfate waters in regions of active volcanoes. Jarosite occurs in association with gypsum, native sulfur, goethite, and native gold. Jarosite deposits in the USSR are located in the southern Ural Mountains, in Kazakhstan, and in the Altai Mountains; other deposits are found in Spain, Czechoslovakia, and France. Pure varieties of jarosite are roasted to yield polishing abrasives with the composition Fe2O3 (called jeweler’s rouge).

A. M. PORTNOV

References in periodicals archive ?
Pale straw yellow is a diagnostic colour for minerals of the jarosite group, which form under oxidising conditions at soil pH between 2.
The jarosite project was $26 million, and the removal efforts cost about $50 million.
Opportunity's instrument also detected jarosite,an iron sulphate mineral.
Quaternary sandstone has a clearly different (sample Pi8) composition, where this fraction is represented by a mixture of chlorite and illite and contains admixture of jarosite (Fig.
It is lithologically represented by brownish, brownish-gray clays with jarosite tarnish and inter-layers of gray, fine-grained sandstones, and by marlaceous and sideritic concretions.
Since 1973, the company had used the jarosite process to recover zinc from waste iron residues.
The physical characteristics as well as previous research (9-12, 21) suggest that it is jarosite ((H,K,Na) [Fe.
The growing problems of ponding jarosite residues may result in fundamental changes in the processing routes for zinc.
A leach-cap zone is coincident with the Extensive leaching of the argillic and sericite alteration zones has resulted in the development of a leach-cap zone marked by the limonites goethite, jarosite and hematite with local presence of the secondary copper minerals turquoise and chrysocolla.
4]) and smectite in the soils, as well as the presence of pyrite, jarosite (K[Fe.
In outcrops and drill cores secondary gypsum and jarosite commonly appear.