Hydroniumjarosite

hydroniumjarosite

melanterite

goethite

hydronium

Images

Formula: (H3O)Fe3+3(SO4)2(OH)6
Sulphate, alunite group, alunite supergroup, hydronium mineral
Crystal System: Trigonal
Specific gravity: 2.9 to 3.26 measured, 3.01 calculated
Hardness: 4 to 4½
Streak: Pale yellow
Colour: Amber-yellow to dark brown
Solubility: Insoluble in water, soluble in hydrochloric acid
Environments

Hydrothermal environments

Hydroniumjarosite occurs in the oxidised zone of rapidly weathering sulphide-bearing rocks; it may be of post-mining formation. It is relatively uncommon because the ubiquitous abundance of alkali ions in surface waters normally precludes its stability. Melanterite and goethite are common associates (HOM).
Most jarosites occurring in nature will probably contain a combination of potassium, sodium and hydronium in the A-position. Hydroniumjarosite is rare and exists only in areas where iron-bearing sulphate solutions have a deficiency of alkali due to rapid oxidation of pyrite accompanied by rapid neutralisation of the solution such as by carbonate rocks to precipitate the jarosite before the alkali in the country rock can be dissolved (AM 50.1595-1607).

Localities

At Cerros Pintados, Tamarugal Province, Tarapacá, Chile, natural hydroniumjarosite has been found (MM 78.535–547).
Hydroniumjarosite from Chile

There are two co-type localities, the Thorez mine, Śródmieście, Wałbrzych, Lower Silesian Voivodeship, Poland and the Staszic Mine, Rudki, Nowa Słupia, Kielce County, Świętokrzyskie Voivodeship, Poland.

At the Staszic Mine, Rudki, Nowa Słupia, Kielce County, Świętokrzyskie Voivodeship, Poland, hydroniumjarosite occurs as crusts deposited on a dolomitic zone in the mine, formed after a gallerly had been opened. At the Thorez coal mine jarosite with a low alkali content was found in a gallery where the temperature was 32oC. The jarosite occurs in the coal bed shale along with melanterite and goethite. The low alkaii content in the mine waters, due to the more rapid decay of the sulphides rather than the rock-forming minerals gives rise to the hydroniumjarosite (AM 50.1595-1607).
Hydroniumjarosite from Poland - Image

Back to Minerals