Jarosite


Also found in: Dictionary, Wikipedia.

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 ?
The XRD and SEM data of both synthetic and natural jarosite after the TAA analysis were almost the same as those of the corresponding untreated jarosite samples (data not shown).
Materials from this zone were fully saturated and partially oxidised with <30% visible pale yellow jarosite mottles.
The soil layers overlying the pyritic gels were composed of medium- to fine-textured soil materials, often with yellow jarosite infillings in the soil matrix and root holes above the sulfide layer, and red/orange iron oxide/hydroxide segregations within the soil matrix and on the soil structural surfaces.
XRD, FTIR and SEM/EDX analysis revealed the presence of bacterial oxidation products such as jarosite and !ron arsenates, as well as low and high corrosion in pyrites and arsenopyrites, respectively.
The spectrometers also found abundant jarosite, an iron-bearing mineral that forms in water on Earth.
The most obvious feature of mineralized zones is the presence of jarosite and secondary iron oxides, hydroxides, etc.
Mintek's plasma-arc smelting technology has been tested on the recovery of lead and zinc from lead blast-furnace slags, and for the treatment of zinc neutral-leach residues and jarosite dump materials.
Jarosite (K[Fe.sub.3][[OH].sub.6][[S[O.sub.4]].sub.2]) is a common product of pyrite oxidation (van Breemen 1973; Dent 1986) and may occur in substantial amounts in well-drained acid sulfate soils (Lin et al.
These deal with the dewatering behaviour of jarosite sludge from the zinc industry, the possible disposal of flue gas gypsum as a cementing agent for backfill and surface deposition with sulphide mill tailings to prevent acid generation, and finally the agglomeration of gold mill tailings for backfill.
Hot acid-leach solution is treated first with more calcine and then with ammonia to precipitate jarosite. There follows a two-stage purification process using different size grades of zinc dust.
In an attempt to correctly identify sulfuric materials when borderline pH values were encountered, I utilised field pH, colour, field descriptions of the occurrence of jarosite, and laboratory analysis.
Fears are mounting of jarosite waste pollution of ground water from one of the storage areas.