ISSN
print 2570-7337
online 2570-7345
Fibroferrit z historické lokality Valachov (Skřivaň) u Rakovníka (Česká republika)
Fibroferrite from the historical locality Valachov (Skřivaň) near Rakovník (Czech Republic)
Klíčová slova
Abstrakt
A historical locality Valachov (Skřivaň) near Rakovník in Czech Republic is a type locality of mineral slavikite. There were discovered several minerals as alunogen, amoniojarosite, botryogen, epsomite, halotrichite, jarosite, melanterite, natrojarosite, pickeringite, gypsum and minerals of copiapite group during the decades. Newly was discovered fibroferrite which forms fine crystalline whitish aggregates at area up to 5 x 10 cm composed by tiny acicular crystals up to 0.2 mm in length. It is trigonal, space group R-3 with following unit-cell parameters refined from X-ray powder diffraction data: a 24.155(3), c 7.633(3) Å and V 3857(1) Å3. The chemical analyses of fibroferrite (mean of 6 points) Na2O 0.17, MgO 1.79, CuO 0.09, Fe2O3 29.11, Al2O3 2.51, SO3 37.03, H2Ocalc. 45.95, total 116.66 wt. % correspond to the empirical formula (Fe0.79Al0.11Mg0.09Na0.01)Σ1.00(SO4)1.00(OH).5H2O. Fibroferrite can be defined as a product of crystallization from wet white gel crusts and after several years breaks down to microcrystalline Al-Mg copiapite.
Soubory
Reference
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