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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 ?
Potential non-bauxite sources for alumina in the United States might include clay, alunite, and anorthosite (Bray 2014).
Analysis focus on the spatial distribution of the main types of altered minerals including kaolinite, alunite, calcite, siderite and halloysite.
1990), alunite from Adams and Rawajfih (1977), and van Breemen (1973) for the value for the observed constant [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] and Nordstrom (1982) for jurbanite.
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.
These acquisitions were a direct result of an ongoing remote sensing and ground reconnaissance program designed to identify intermediate to high-sulfidation prospects by targeting strong alunite with kaolinite and illite alteration systems.
Drilling at the Eastern Zone will start with the initial testing of the first group of target areas including: Alunite Hill, Spicerite Graben, Vinegaroon and Cat Hill.
The risks posed by exposure to Al are controlled by the reactivity of Al-bearing minerals, which in mine wastes are most commonly the sulphates alunite and basaluminite.
Initial leach tests conducted on alunite samples from Lake Chandler indicate that approximately 90% of the potash in Lake Chandler can be successfully dissolved under relatively mild conditions (approximately 60 minutes leach time at 160DEG and 1000-2000kPa) using ammonia as the leachant in a standard autoclave system.
Dating of alunite shows that supergene alteration extended over a long period from 44 to at least 21 Ma (Rowland and Clark 2001).
His first mount is aboard Alunite, who lines up in a competitive ten-furlong handicap in which the opposition includes John Sadler's Mukhalif, on whom Dettori landed the 1999 Italian Derby for Godolphin.