The Late Cretaceous diamondiferous pyroclastic kimberlites from the Fort à la Corne (FALC) field, Saskatchewan craton, Canada: Petrology, geochemistry and genesis

The Late Cretaceous (ca. 100 Ma) diamondiferous Fort à la Corne (FALC) kimberlite field in the Saskatchewan (Sask) craton, Canada, is one of the largest known kimberlite fields on Earth…

Continue ReadingThe Late Cretaceous diamondiferous pyroclastic kimberlites from the Fort à la Corne (FALC) field, Saskatchewan craton, Canada: Petrology, geochemistry and genesis

Geochemical composition of sedimentary rocks and imprint of hydrothermal fluid flow at the Variscan front – an example from the RWTH-1 well (Germany)

The mineralogical and chemical characteristics of Palaeozoic rocks in the northern Eifel Mountains provide information on the sedimentary provenance in the NW Rhenohercynian Basin and on the mineralogical and hydrothermal control of trace element abundance. Elements mainly bound to illite (i.e. V, Ni, Rb, Sr, Cu, Ba) can be distinguished from elements predominantly controlled by chromite (Cr) and zircon (Zr). Lower Devonian and Upper Carboniferous units have similar (more…)

Continue ReadingGeochemical composition of sedimentary rocks and imprint of hydrothermal fluid flow at the Variscan front – an example from the RWTH-1 well (Germany)

Minerals of the pyrochlore group as niobium-ore

In comparison to other commodities, e.g. gold, niobium-ores are related to a small number of igneous rocks, in particular carbonatites and genetically-related silicate-carbonate rocks.
Within these rocks niobium is segregated principally in oxide minerals such as the pyrochlore-microlite solid solution series (Ca,Na)2(Nb,Ta)2O6(O,OH,F) and niobian perovskite (Ca,Na)(Ti,Nb)O3. At least four other Nb minerals can occur in sufficient quantities to dominate or affect the niobium content of a carbonatite. They include ferrocolumbite FeNb2O6, fersmite (Ca,REE,Na)(Nb,Ta,Ti)2(O,OH,F)6, niocalite Ca4NbSi2O10(O,F), and wöhlerite NaCa2(Zr,Nb)Si2O8(O,OH,F). Pyrochlore is the dominant niobium host and the only mineral (more…)

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Wakefieldite-(La), LaVO4 , a new mineral species from the Glucksstern Mine, Friedrichroda, Thuringia, Germany

Wakefieldite-(La), ideally LaVO4, is a new mineral from the long abandoned Glücksstern Mine, Gottlob hill, Friedrichroda, Thuringia, Germany. The mineral occurs as light pinkish to brown prismatic crystals up to 0.5 mm in length. Wakefieldite-(La) is associated with hausmannite, baryte and gottlobite. The streak is white, the Mohs hardness 4 and the luster adamantine. The crystals are transparent to translucent. Electron microprobe analysis (more…)

Continue ReadingWakefieldite-(La), LaVO4 , a new mineral species from the Glucksstern Mine, Friedrichroda, Thuringia, Germany