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…)

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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

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

The RWTH-1 well within Aachen offers outstanding conditions for the study of Devonian to Carboniferous sedimentary rocks in the NW Rhenohercynian close to the Brabant Massif. The geochemical data obtained from core and cutting samples provide information on the depositional history (Lower Devonian, Siegenian, to Upper Carboniferous, Namurian to Westphalian) of the NW-Rhenohercynian basin and set constraints on the mineralogical and hydrothermal control on trace element abundance in the northern Eifel region (more…)

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

Assessment of acid-rock-drainage from epithermal Au-Ag mineralisations, Rio Turbio, San Juan, Argentina

The Veladero district in the Rio Turbio Basin (San Juan, Argentina) consists of at least eight alteration zones within an area of 14 km2. It contains several large bulk-tonnage Au-Ag-deposits in altered, silicified volcanic rocks. The oxidized zone extends to considerable depth. The Veladero orebody occurs as a 750 m x 3000 m tabular body (more…)

Continue ReadingAssessment of acid-rock-drainage from epithermal Au-Ag mineralisations, Rio Turbio, San Juan, Argentina