Publication details
Revize a nové nálezy fosfátů na historickém nalezišti Černovice u Tábora
| Title in English | A revision and new findings of phosphates from the historical locality Černovice near Tábor (Czech Republic) |
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| Authors | |
| Year of publication | 2017 |
| Type | Article in Periodical |
| Magazine / Source | Bulletin Mineralogie Petrologie |
| MU Faculty or unit | |
| Citation | |
| Web | http://bullmineral.cz/paper/163 |
| Keywords | Czech Republic;Černovice;Na Zoubku;Raman spectra;uranium minerals;phosphate occurence;strengite;natrodufrénite;kidwellite;variscite;fluorwavellite |
| Attached files | |
| Description | An interesting supergene phosphate and uranium mineral association was found on the historical wavellite occurrence Černovice near Tábor (Vysočina region, Czech Republic). Phosphates are bound to cracks and cavities in graphitics gneisses and quartzites. Beraunite forms radially fibrous greenish, greenish brown to reddish brown aggregates up to 1.5 mm in size. Carnotite was found as yellow powdery aggregates up to 1 mm accross in association with metatorbernite, phosphosiderite and metavariscite. Historically known wavellite has been redefined as fluorwavellite. It is the most abundant phosphate in the studied mineral association, it usually occurs as spherical aggregates up to 5 mm in size. Its colour is significantly zonal, from blue in the centre of aggregates to yellow in the marginal part. Phosphosiderite-metavariscite forms light green crusts on quartz crystals thickeness up to 0.1 mm. Cacoxenite occurs as yellow crusts and radial aggregates up to 0.2 m in size. Kidwellite occurs as green spherical aggregates up to 0.1 mm in size. Leucophosphite was found only as a very rare yellow to yellowish green tabular crystals and their aggregates up to 0.01 mm in size on hemispherical beraunite.Metatorbernite forms green tabular crystals up to 3 mm in size. Natrodufrénite was found as dark green to bluish green aggregates with light green or yellowish green zones forming radial aggregates up to 1.5 mm in size. Strengite was observed as spherical aggregates of white, light gray, beige or yellow to orange color up to 4 mm in size in four different mineral associations. Turquoise forms apple green zonal crystals up to 0.1 mm in size. Two varieties of variscite was observed; white variscite forms crusts on the surface of spherical aggregates of the strengite and green variscite was found as light green crusts of thickness up to 1 mm in size. X-ray powder diffraction patterns and quantitative chemical composition for determined mineral phases are given in the paper. |