Ankerite

About: Ankerite is a research topic. Over the lifetime, 859 publications have been published within this topic receiving 23960 citations.

Rare-earth element minerals in four carbonatites near Gatineau, Quebec

Abstract: Near Gatineau, Quebec lens-shaped and vein-form carbonatites cut Precambrian fenitized biotite gneiss and quartzite. Major minerals are calcite, barite, fluorapatite and hematite and variable amounts of celestite, dolomite, strontianite, aegirine, magnesio-arfvedsonite, microcline, albite, phlogopite, fluorite, rutile, quartz, monazite and REE fluocarbonates. The carbonatites are distinctly rich in rnagnesium (0.3-12.2 wt.% MgO) manifest by silicates in the veins and silicates andfor ankerite in the lenses. They are also high in lanthanides (La + Ce + Nd + Gd + Er * Yb from 370 to 41000 ppm), strongly enriched in LREE (LalYb ratios ranging from 69 to 1000) and high in barium (2.7-19,8 wt.% BaO). The BaO/SrO ratios vary between 0.9 and 66. Where phosphates are the sole important lanthanide bearers, fluorapatite contains 1.2-1.7 wt.o/o CerO, (similar to apatite in nearby fenite), where associated with REE fluocarbonate, it contains 0.25 to 0.35 wt.% CerO. only, but with concomitant increase in the bulk-rock cerium. Ce-rich apatite appears to be primary and relatively unaltered but the Ce-poor apatite is either leached or secondary. Parisite and synchysite formed in situ through the breakdown of apatite, and unidentifled REE fluocarbonates were deposited from solution after leaching and transportation. Mineral association and compositions suggest low temperature and strong oxidation. Calcite and dolomite equilibrated at 240-300'C. It is suggested that emplacement was hydrothermal and controlled by faults of the Ottawa-Bonnechere rift svstem.

Potassic and sodic alteration accompanying gold mineralization in the Rattling Brook Deposit, western White Bay, Newfoundland Appalachians

Abstract: Gold mineralization is hosted by foliated, late Proterozoic granitoid rocks of the Rattling Brook area, western White Bay, Newfoundland. The mineralization is associated with sulfides and occurs in veins and fractures and in disseminated form. Associated hydrothermal alteration occurred in two stages. During stage 1 potassic alteration the host granodiorite was hydrothermally converted over large areas to a rock of granitic composition through the formation of microcline and sericite by pervasive reaction of plagioclase and mafic minerals with hydrothermal fluids. Stage 2 sodic alteration is restricted to fractures, veins, and vein selvages and overprints both stage 1 alteration and unaltered rock. It consists of microcrystalline to fine-grained albite with lesser amounts of ankerite, quartz, sericite, and siderite accompanied by pyrite, arsenopyrite, and gold. Altered rocks are enriched in K, Na, Au, As, S, and CO 2 , weakly enriched in W, Sb, and Br, and depleted in heavy rare earth elements. The gold mineralization and alteration extends into unconformably overlying Eocambrian to Cambrian sediments. The absence of deformation in the alteration and ore assemblages suggests that the mineralization postdated Acadian deformation in the area and thus is Late Silurian or younger. Both alteration episodes are considered to be part of the same hydrothermal event, which resulted in formation of the large low-grade deposit. CO 2 -rich fluids circulated through the crust along major structures, leached elements from a variety of rocks, and redeposited them in fractures and veins within overlying granitoids and sedimentary rocks. Stage 1 fluids initially permeated along grain boundaries and converted the host to a rock of granitic composition. Subsequent increases in the a (sub Na+) /a (sub K+) ratio and/or temperature were accompanied by fracturing, albitization, and deposition of sulfides and gold during stage 2.

Investigation on Inorganic Constituents in Indian Coal and Emission Characteristics of the Particulates (PM2.5 and PM10)

Abstract: The micro-analysis of the inorganic constituents was performed on a tertiary Indian coal sample using computer-controlled scanning electron microscopy (CCSEM). A laboratory combustion experiment of the coal was also carried out to reveal the emission characteristics of particulate matters (PM2.5 and PM10). The results show the presence of major minerals like clay minerals, quartz, pyrite, and pyrrhotite forming the bulk of the mineral matter including some minor minerals, such as calcite, dolomite, ankerite, barite, oxidised pyrrhotite, and gypsum in the sample. The particle size distribution (PSD) of the included minerals is generally observed to be finer than that of the excluded ones in the coal. As a consequence, the coals rich in included minerals have smaller particles, which may affect its reactivity. The ratio of included to excluded minerals is found to be higher in majority of cases. It is found that Si mostly occurs as quartz and clay minerals, while Al mostly occurs as silicate minerals. Fe is...

Transformation of minerals at the boundary of magma-coal contact zone: case study from Wolonghu Coal Mine, Huaibei Coalfield, China

Abstract: Mesozoic and Cenozoic magma activity in the Wolong Lake mining area of Huaibei is frequent, and the degree of magma intrusion into coal seams remarkable. On the one hand, magma intrusion affects the utilization of coal resources; on the other hand, the macro and trace elements in coal are redistributed to form new mineral types. This study uses the Wolong Lake magma intrusion coal seam as a research object. The mineral paragenesis for igneous rock, coke, and thermally-altered coal in an igneous intrusion zone is studied using SEM, XRD, and Raman spectroscopy. During igneous intrusion, the temperature and pressure of igneous rock metamorphose ambient low-rank coal to high-rank coal and coke. The response mechanism of minerals and trace elements to magmatic intrusion is discussed. The results are: ① SEM analysis shows that ankerite and pyrite are formed from magma intrusion. Both minerals are strongly developed in the magma-coal contact zone, and less well developed in thermally-altered coal. ② XRD analysis shows that igneous intrusion strongly influences the types and content of minerals in coke and thermally-altered coal. In addition to the increase amounts of ankerite and pyrite, chlorite, serpentine, and muscovite, and other secondary minerals, are generated following igneous intrusion. ③ Raman analysis suggests that thermally-altered coal possesses the characteristics of both pyrite and coke. Coke from the magma-coal boundary zone possesses the typical characteristics of pyrite. Igneous rock contains a mineral similar to pyrite, confirmed by both having similar Raman peaks. The scattering intensity of Ag indicates that the formation pressure of pyrite increases from thermally-altered coal via the boundary between the coke zone and the igneous rock.