Also found in: Dictionary, Wikipedia.
Related to Alunite: adularia


KAl3(SO4)2(OH)6 A mineral composed of a basic potassium aluminum sulfate; it occurs as a hydrothermal-alteration product in feldspathic igneous rocks and is used in the manufacture of alum. Also known as alumite; alum rock; alumstone.



a mineral of the complex sulfate group, with extra (OH)- anions. The chemical composition KA13[SO4]2(OH)6 sometimes includes admixtures of Na+ and Fe3+. Alunite crystallizes very rarely in a trigonal system. The mineral is mostly found in the form of fine-grained or friable earthy, sometimes fibrous, aggregates. The color is white, with grayish, yellowish, and reddish tints. The hardness of alunite on the mineralogical scale is 3.7–4.5; its density is 2,600–2,800 kg/m3. Alunite is formed by reworking acid and neutral volcanic rocks that contain orthoclase with hydrothermal sulfuric acid solutions and also by the action of sulfate surface water on aluminiferous rocks. Rocks containing alunite are a source of alum, alumina, potassium salts, and other substances.


References in periodicals archive ?
In order to have different criteria for evaluating performance of the algorithms in this study, synthetic target were created from the pure spectral signature of alunite with various degrees of mixture (f= 10%, 20%, 30%, 40%, y 100%).
Potential non-bauxite sources for alumina in the United States might include clay, alunite, and anorthosite (Bray 2014).
Alunite and kaolinite can be uniquely identified by their spectral characteristics (position and shape of absorption troughs between 2.
The advanced argillic alteration is characterized by an assemblage of Amorphous silica + cristobalite + alunite + tridymite + kaolinite + quartz + jarosita + sulfur; although, in some cases some of the mentioned minerals are absent.
Finally, certain minerals found predominantly in altered areas, including halloysite, siderite and alunite, [3, 17], have been used to identify subsurface reservoirs.
Larsen (1942a) reported the presence of alunite in the Clay Canyon deposit, as rounded, creamy white to dark gray nodules up to 20 cm in diameter, incorporating about one third of their weight in quartz.
His mount, Alunite, found stablemate, Narrative, ridden by John Carroll, too good in a competitive mile and a quarter handicap.
The former was a Gowran Park maiden winner for John Oxx at two, and took to the dirt surface well, despite worries beforehand, beating Dettori's mount Alunite.
His mount, Alunite, found stablemate, Narrative, too good and then previous winner, Seba, went down to another stable companion, Infinite Spirit.
In Azerbaijan, the Dashkesan iron (includes cobalt) and Zaginsky alunite (aluminium) deposits were developed with the establishment of kombinats for refining and primary processing.