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Hollandit a kryptomelan z Poniklé u Jilemnice, Česká republika
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SYSNO ASEP 0451735 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Ostatní články Title Hollandit a kryptomelan z Poniklé u Jilemnice, Česká republika Author(s) Jirásek, J. (CZ)
Matýsek, D. (CZ)
Vaculíková, Lenka (UGN-S) RID, ORCID
Sivek, M. (CZ)Number of authors 4 Source Title Bulletin mineralogicko-petrologického oddělení Národního muzea v Praze - ISSN 1211-0329
-, č. 23 (2015), s. 1-6Number of pages 6 s. Publication form Online - E Language eng - English Country CZ - Czech Republic Keywords hollandite supergroup ; coronadite group ; mineralogy ; infrared spectroscopy ; Poniklá Group Subject RIV DB - Geology ; Mineralogy R&D Projects ED2.1.00/03.0082 GA MŠMT - Ministry of Education, Youth and Sports (MEYS) LO1406 GA MŠMT - Ministry of Education, Youth and Sports (MEYS) Institutional support UGN-S - RVO:68145535 Annotation At historical iron ore mining site near Poniklá, famous for natrodufrénite occurence, were described two minerals from the coronadite group (hollandite supergroup) - hollandite and cryptomelane. They are present in cavities and fissures of brecciated iron ore with quartz. Both form of greyish-black to black reniform aggregates with dull to sub¬metallic lustre several milimeters thick, covering the areas mostly up to 10 cm2. Submicroscopic layers of hollandite are alternating with the same of cryptomelane. Occurence of minerals from coronadite group was confirmed by the powder XRD, as well as by IRS. Chemical data from EMPA-WDS confirmed presence of both phases with composition close to its end-members, with minor admixture of Ca2+, Sr2+ a Fe3+, in case of hollandite also K+. We believe that these minerals were originally described as psilomelane and pyrolusite in 19th century from the Poniklá. Co-existence of iron and manganese oxidic minerals well corresponds to iron-rich residual deposits, where both elements remain fixed in relatively stable minerals and their mobility remains unimportant even during lateritic weathering and carst formation. Workplace Institute of Geonics Contact Lucie Gurková, lucie.gurkova@ugn.cas.cz, Tel.: 596 979 354 Year of Publishing 2016 Electronic address http://www.nm.cz/publikace/archiv.php?id=13
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