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n.1.(Min.) A soft black, iron ore, nearly earthy, a hydrous silicate of iron.
References in periodicals archive ?
Black crystals of cronstedtite with triangular cross-section, displaying only {20[bar.2]1} and {0001} faces, as well as compact masses of cronstedtite, were once found on hisingerite, marcasite, pyrite, siderite and rhodochrosite.
Associated minerals are: lepidolite, microcline, elbaite, topaz, beryl, quartz, fluorapatite, barite, calcite, pyrochlore, uranpyrochlore, uranmicrolite, bismuth, ustarasite, kaolinite and hisingerite.
The altered skarns contain, in addition, datolite, hisingerite, quartz, calcite, sepiolite, and siderite (Bulavko, 1984).