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Ankerite
About: Ankerite is a research topic. Over the lifetime, 859 publications have been published within this topic receiving 23960 citations.
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TL;DR: The gold ore bodies are mineralized segments of folded Precambrian iron formations separated by shear zones, diabase dikes, and barren iron formation as discussed by the authors, the type of iron formation that acts as principal host is banded siderite-quartz rock.
Abstract: The gold ore bodies are mineralized segments of folded Precambrian iron formations separated by shear zones, diabase dikes, and barren iron formation. The type of iron formation that acts as principal host is banded siderite-quartz rock. Belts of this rock are enclosed in chlorite schist, some of which is chromium-rich. Gold-bearing hydrothermal solutions, rising along the axes of plunging folds, preferentially replaced bands of siderite in the iron formation. Early solutions altered the schist wall rock to green chromian sericite schist and deposited pyrite. Arsenopyrite, pyrrhotite, chalcopyrite, quartz, ankerite, and most of the gold were introduced during the later, principal stage of mineralization, from an unknown source or sources.
12 citations
TL;DR: The El Dorado Au-Cu deposit is located in an extensive intra-caldera zone of hydrothermal alteration affecting Upper Cretaceous andesites of the Los Elquinos Formation at La Serena (≈ 29°47′S Lat., 70°43′W Long., Chile).
Abstract: The El Dorado Au-Cu deposit is located in an extensive intra-caldera zone of hydrothermal alteration affecting Upper Cretaceous andesites of the Los Elquinos Formation at La Serena (≈ 29°47′S Lat., 70°43′W Long., Chile). Quartz-sulfide veins of economic potential are hosted by N25W and N20E fault structures associated with quartz-illite alteration (+supergene kaolinite). The main ore minerals in the deposit are pyrite, chalcopyrite ± fahlore (As/(As + Sb): 0.06−0.98), with electrum, sphalerite, galena, bournonite-seligmanite (As/(As + Sb): 0.21−0.31), marcasite, pyrrhotite being accessory phases. Electrum, with an Ag content between 32 and 37 at.%, occurs interstitial to pyrite aggregates or along pyrite fractures. Pyrite commonly exhibits chemical zonation with some zones up to 1.96 at.% As. Electron probe microanalyses of pyrite indicate that As-rich zones do not exhibit detectable Au values. Fluid inclusion microthermometry shows homogenization temperatures between 130 and 352 °C and salinities between 1.6 and 6.9 wt.% NaCl eq. Isotope data for quartz, ankerite and phyllosilicates and estimated temperatures show that δ18O and δD for the hydrothermal fluids were between 3 and 10‰ and between −95 and −75‰, respectively. These results suggest the mineralizing fluids were a mixture of meteoric and magmatic waters. An epithermal intermediate-sulfidation model is proposed for the formation of the El Dorado deposit.
12 citations
12 citations
TL;DR: In this article, the potential of unburnt colliery spoil as a medium for plant growth is assessed for spoil heaps in the West Riding of Yorkshire with surface spoil pH values well below 4.5.
Abstract: THE more usual methods of soil extraction and chemical analysis are not entirely applicable to assessment of the potential of unburnt colliery spoil as a medium for plant growth. This is particularly true for spoil heaps in the West Riding of Yorkshire with surface spoil pH. values well below 4.5. Such spoil often contains FeS2 which oxidizes to produce Fe++, SO4−− and H+. It may also contain the carbonate mineral ankerite which is potentially capable of neutralizing the acidity. These reactions produce large quantities of soluble salts, chiefly sulphates.
12 citations
TL;DR: In this article, the authors focused mainly on the post-depositional changes that occurred during shallow to deep burial diagenetic evolution and subaerial weathering of the Geirud Formation in the Alborz Mountain Range, north of Iran.
12 citations