Publication details
Fibroferrit z historické lokality Valachov (Skřivaň) u Rakovníka (Česká republika)
| Title in English | Fibroferrite from the historical locality Valachov (Skřivaň) near Rakovník (Czech Republic) |
|---|---|
| Authors | |
| Year of publication | 2014 |
| Type | Article in Periodical |
| Magazine / Source | Bulletin mineralogicko-petrologického oddělení Národního muzea v Praze |
| MU Faculty or unit | |
| Citation | |
| Web | https://publikace.nm.cz/periodicke-publikace/bmpholnrhmvp/22-2/fibroferrit-z-historicke-lokality-valachov-skrivan-u-rakovnika-ceska-republika |
| Keywords | fibroferrite; powder X-ray diffraction data; unit-cell parameters; chemical composition; Valachov hill; Czech Republic |
| Description | A historical locality Valachov (Skřivaň) near Rakovník in the Czech Republic is a type locality of mineral slavikite. During the decades there were described several minerals as alunogen, amoniojarosite, botryogen, epsomite, halotrichite, jarosite, melanterite, natrojarosite, pickeringite, gypsum and minerals of copiapite group. 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) A and V 3857(1) A3. 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)?1.00(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. |