Browsing by Subject "diabases"

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Access status: Open Access ,
Tlenki manganu z diabazów Niedźwiedziej Góry koło Krakowa
(Wydawnictwa AGH, 2009) Muszyński, Marek; Rzepa, Grzegorz; Skowroński, Andrzej
Black manganese oxides from the polymineral veins found in 1998 in the so-called diabases of Niedźwiedzia Góra near Kraków have been identified (XRD, IR, DTA-TG, SEM/EDS, EPMA/WDS) as intermediate members of the rancieite-takanelite series. In comparison with the minerals of this series described in the literature, they reveal elevated contents of iron and barium and relatively low contents of calcium. In the probable succession of components of the veins mentioned, the Mn oxides occupy the before last position: goethite +/- saponite $\to$ <b>tension</b> $\to$ barite, thin prismatic-acicular quartz $\to$ <b>leaching</b> $\to$ Mn oxides, prismatic quartz. They must have crystallized from descensive waters associated with surface weathering of the diabases, which took place when overlaying Carboniferous rocks had been eroded. The weathering diabases were a probable source of manganese.
Access status: Open Access ,
Żelazowo-żelazawe odmiany sepiolitu i saponitu z diabazów z Niedźwiedziej Góry koło Krakowa
(Wydawnictwa AGH, 2008) Gaweł, Adam; Muszyński, Marek; Pieczka, Adam; Skowroński, Andrzej; Stoch, Paweł
In fracture veins found in the so-called diabases of Niedźwiedzia Góra near Cracow the authors have identified ferriferrous varieties of sepiolite: $Ca_{0.09}(Mg_{2.35}Fe^{3+} _{0.82}Fe^{2+} _{0.33}Mn_{0.05})_{\Sigma 3.55}[(Si_{5.92}Al_{0.07}Fe^{3+} _{0.02})O_{15}](OH)_{2} \cdot 6H_{2}O$ and saponite: $(Ca_{0.018}K_{<0.01})(Mg_{1.55}Fe^{3+} _{0.61}Fe^{2+} _{0.38}Al_{0.16}Ti_{0.01})_{\Sigma 2.71}[(Si_{3.46}Al_{0.37}Fe^{3+} _{0.17})O_{10}] (OH)_{2} \cdot 4H_{2}0$, two minerals rarely occurring in the nature. They are accompanied mainly by quartz (sometimes with chalcedony) and calcite, whereas less frequently by pyrite, marcasite, sphalerite, barite, fluorapatite and Ti-Fe oxides (ilmenite?). The veins represent a distinct system that must be interpreted as a result of epithermal postmagmatic activity. The sepiolite rich in iron, the minerals of the $SiO_2$ group, calcite, barite and Fe and Zn sulphides crystallized directly from solutions in rock fractures. The iron-rich saponite is, in turn, a product of alteration of the diabase rubble present initially in the fractures (apatite and Ti-Fe oxides are its relicts), affected by these solutions. The saponite must have originated as a ferrous variety in a reducing environment. Its current, ferriferrous character is an effect of later changes imparted by descending, oxygen-rich waters, percolating through the fractures after the erosion removed overlaying Carboniferous rocks and an upper part of the diabase sill.