Formation Of Muscovite Research Articles

Processing and characterization of geopolymer and sintered geopolymer foams of waste glass powders

Geopolymer foams of fine and coarse waste glass (WG) powders were prepared using an activation solution of NaOH (8 M) and Na2SiO3. The effects of WG powder particle size, solid/liquid ratio (S/L = 1, 1.5, and 2) and Al foaming agent content (2–20 wt%) on the expansion and temperature behavior of the slurries were determined in-situ using a laser sensor and a thermocouple, respectively. The geopolymer foams processed using a coarse WG powder slurry, S/L = 2, and 2 wt% Al, were further sintered at 600, 700, 725, and 750 °C. The compression strengths and thermal conductivities of the geopolymer and sintered geopolymer foams were also determined. The slurry expansions continued until about a maximum, and the temperatures of the slurries increased to a maximum, 85–88 °C. At the maximum temperature, the slurry evaporation and the resultant increase in the S/L ratio limited the slurry expansion. Increasing the Al content decreased the final density of the foams (238–555 kg m−3), while the coarse powder slurries resulted in lower densities than the fine powder slurries. Three crystal phases, muscovite, sodium aluminum silicate hydrate, and thermonitrite, were determined in the geopolymer foams. The muscovite formation was noted to be favored at high S/L ratios. During sintering, the partial melting of glass particles started after about 700 °C, while sintering above this temperature decreased the final density of the foams. The reduced density above 700 °C was ascribed to the release of CO2 due to the decomposition of thermonitrite. Both the compressive strength and thermal conductivity of the geopolymer and sintered geopolymer foams increased with increasing foam density. The highest increase in the compressive strength and reduction in the density were seen in the geopolymer foams sintered at 750 °C.

Influence of Mineralogical and Micro-Structural Changes on the Physical and Strength Properties of Post-thermal-Treatment Clayey Rocks

This study investigates the effects of thermal treatment and exposure time on the physico-mechanical properties related to the mineralogical and structural changes of clayey rocks at temperatures of up to 1000 °C. Vitric-crystal tuffs were studied because they show different engineering behavior than most rocks at high temperatures. The samples were heated at the rate of 10 °C/min, exposed to the desired temperatures for 2 h, and cooled at room temperature. Then a series of geo-mechanical tests was performed, thin sections and SEM images were prepared, and XRD and DTA analyses were carried out. Depending on the increase in the high temperature, the strength increased by 50% in the samples exposed to 400 °C, and a higher strength value was recorded than the initial strength even at 600 °C. Thin sections and SEM images showed that while the primary void ratio decreased until 400 °C because of the melting and expansion of clay-sized particles, new micro-cracks formed at the boundaries of quartz and plagioclase. Although the secondary micro-crack ratio increased, the sintering, cementation, and fusing between clay minerals were the main reasons for the increase in strength until 600 °C. After this temperature, the strength suddenly decreased due to the transformation of minerals, especially the formation of muscovite, and the development of secondary glasses. These changes were observed in DTA peaks and XRD analysis results. The unit weight decreased until 600 °C due to dehydration of absorbed water and hydroxylation reactions of the clay minerals and then remained constant. Despite the decrease in strength, the filling of primary voids by molten clay minerals and the formation of high-density minerals like clinoptilolite and muscovite prevented decreases in unit weight after 600 °C. In addition, the investigation of the exposure time showed that 90% of the strength loss occurs within the first 20 min at the threshold temperature, after which time does not affect the change in strength.

Effect of Locust Bean Pod Ash and Eggshell Ash on the Mortar Compressive and Flexural Strengths of Cement Blends

An increase in the generation of biogenic wastes such as locust bean pods and eggshells coupled with the need to drive sustainability in the cement industry has led the use of these wastes as cement replacement materials. The paper aims to investigate the effect of locust bean pod ash (LBPA) and eggshell ash (ESA) on the mortar compressive and flexural strength of ternary cement blends. The LBPA was obtained by calcining locust bean pod (LBP) at various temperatures of 800-900 °C and time of 60–120 minutes at an interval of 50 °C and 30 minutes respectively to determine the optimal conditions. The chemical composition of Ordinary Portland cement (OPC), LBPA and ESA were obtained via X-ray Fluorescence (XRF) Spectrometer and LBPA chemical composition did not satisfy one of the requirements specified by ASTM C618-01 (2001) with SiO 2 + Al 2 O 3 +Fe 2 O 3 of 30.42 wt. % which is less than 50 wt. %, but satisfies SO 3 content requirement of 0.7 wt. % and Loss on Ignition (LOI) of 7.12 wt. % and contains 19.42 wt. % CaO which is within the range of 10-30 wt. % CaO is class C pozzolan. The compressive strength of blended cement mortars at the early age of 2 and 7 days produced better strengths for cement blends with higher ESA content than LBPA especially at LBPA/LBPA-ESA ratio of 0, 0.4 and 0.6 for 2.5 wt. % cement replacement respectively. The early strength gain could be attributed to the provision of more nucleation sites by ESA inclusion which results in the acceleration of cement hydration rate. On the other hand, the enhanced strengths at 28 days of cement blended with various replacement from 2.5–10 wt. % could be attributed to the pozzolanic reaction between the available lime and reactive silica from LBPA despite clinker diminution which was close to control. Another reason for enhanced strength' could be attributed to the increased potassium content by an increase in LBPA content resulting in a gradual strength gain (retarder) muscovite formation K 2 Al 2 Si 6 Al 4 O 20 (OH) 4 . All cement blends experienced an increase in the mortar compressive and flexural strengths as the curing day progressed with some blends producing enhanced strength compared to control especially with 1.5 ESA1LBPA produced the best strength at 50.15 (6.82) N/mm 2 against 48.80 (6.80) N/mm 2 . This enhanced strength could be related to the pozzolanic activity and the high potassium content from LBPA despite clinker diminution, especially at 28 days.

Petrology of the tin-bearing granite-leucogranites of the Piaoak Massif, Northern Vietnam

The Piaoak tin-bearing granite-leucogranites located in the Caobang Province of Northern Vietnam compose a stock-like hypabyssal body. Host rocks are represented by Early Devonian carbonate sequences and Early Triassic “black” shales. The geochronological age of the Piaoak granite-leucogranites corresponds to the Late Cretaceous: T = 83.5 ± 6.2 Ma, 87Rb/86Sr method; T = 89.7 ± 1.0 Ma, 39Ar/40Ar method. The massif has a simple basic to acid order: two-mica and muscovite granite-leucogranite → raremetal aplites, pegmatites → tin-bearing greisens and hydrothermal veins. The petrographic and microstructural studies revealed a sharp change in crystallization conditions of the granite-leucogranite magma at the late magmatic stage and formation of muscovite via incongruent melting of protolithionite. The study of melt and coexisting fluid inclusions showed that solidus crystallization occurred under fluid-saturated conditions at 635–600°C. In composition, the granite-leucogranites of the Piaoak Massif correspond to the raremetal-plumasite geochemical type (according to L.V. Tauson), and reach Li-F facies in terms of their rare-element composition. The composition of aplites and pegmatites demonstrates that granite-leucogranite magma did not accumulate lithophile and volatile components in the residual melt during differentiation, but was initially enriched in rare-metals. It is most probable that the melt was generated from Proterozoic lithotectonic complexes and overlaying Lower Triassic “black” shales.

An exhumation pressure–temperature path and fluid activities during metamorphism in the Tseel terrane, SW Mongolia: Constraints from aluminosilicate-bearing quartz veins and garnet zonings in metapelites

The Tseel terrane of the Central Asian Orogenic Belt, SW Mongolia, contains a record of amphibolite-facies (locally granulite-facies) metamorphism and multiple igneous intrusions. However, the metamorphic history of the terrane and the relation of metamorphism to the intrusion of granitoids remain uncertain. In this study, we investigated pelitic gneisses and aluminosilicate-bearing quartz veins located at various distances from a granitoid body in the central part of the Tseel terrane.The pelitic gneisses are composed mainly of garnet (Grt)+biotite (Bt)+plagioclase (Pl)+sillimanite (Sil)+quartz (Qtz). Garnet in the pelitic gneiss located far from the granitoid shows compositional zoning, characterized by decreases in Ca and Mn from core to rim, and increases in Fe and Mg, along with minor retrograde zoning at the outermost rim. The P–T path during garnet growth was estimated by garnet isopleth thermobarometry based on a P–T pseudosection and by conventional Grt–Bt geothermometry and Grt–Bt–Pl–Qtz geobarometry. The two approaches yield similar P–T paths, with the decompression P–T path extending from the kyanite (Ky) stability field (560±10°C and 6.5±0.5kbar) to the sillimanite stability field (600±5°C and 3.8±0.5kbar), accompanied by a slight increase in temperature (by 40–50°C). Garnet grains in pelitic gneisses located near the granitoid body lack a high-Ca core and yield P–T conditions of the sillimanite stability field, suggesting the local thermal effect of a granitoid intrusion at shallow crustal depths (<∼20km).Aluminosilicate-bearing quartz veins in the pelitic gneisses contain kyanite, sillimanite, and andalusite (And) at their margins. The textural relations among aluminosilicate polymorphs in the veins indicate their formation in the order of Ky→Sil→And. Microthermometric analyses of fluid inclusions reveal that these veins formed in the kyanite stability field, that corresponds to the growth of high-Ca garnet cores in the pelitic gneiss. The precipitation of coarse-grained kyanite in fractures was probably assisted by the focused flow of fluid produced by a dehydration reaction (i.e., the garnet-in reaction). After the main period of vein growth, the replacement of kyanite by sillimanite and andalusite occurred in association with the formation of muscovite in the veins. These reactions were probably facilitated by fluid supply from granitoids at shallow crustal depths.

10.1007/s11477-008-1001-7

The Lena gold district is situated in the fold-and-shear belt of the southern framework of the Siberian Platform. The gold deposits are hosted in the Riphean-Vendian Khomolkho and Aunakit formations, revealing the strict control of ore mineralization by folding and shearing. The microstructure of metasomatically altered ore-bearing carbonaceous sedimentary rocks at the Sukhoi Log, Golets Vysochaishy, and Verninsky deposits (the latter includes the Pervenets vein zone) testifies to parallelism in the development of shearing, foliation, and ore-forming metasomatism. The local pressure gradients are marked by removal of silica from pressured zones into opened cleavage fractures and pockets. Two metasomatic stages are recognized: (1) early sodic metasomatism, which is characterized by the assemblage of magnesian siderite and paragonite, and (2) late potassic metasomatism, with formation of muscovite in association with sideroplesite and ankerite. The rocks altered at the early stage are distinguished by elevated Ni, Cr, and probably PGE contents. The second stage, close in age to the emplacement of Hercynian granitic plutons, was accompanied by the gain of chalcophile metals and deposition of the bulk of gold. In mineral composition, the metasomatic rocks are close to beresites, but the alteration differed in somewhat elevated alkalinity, so that microveinlets of albite and potassium feldspar occur in the ore zone together with muscovite. The ratio of modal muscovite to paragonite contents in orebodies is substantially higher than in the surrounding metasomatized rocks. This ratio directly depends on the degree of rock permeability and the intensity of the flow of ore-forming solutions. Carbonaceous matter (CM) in the ore zone underwent reworking and redeposition. CM is graphitized to a lesser extent than in the rocks affected by regional metamorphism. The spatial distribution of CM containing nitro and amino groups indicates more oxidizing conditions in the zone of ore deposition than at a distance from this zone. The temperature of metasomatic processes estimated from the muscovite, muscovite-paragonite, and chlorite mineral thermometers and fluid inclusions in quartz was 300–350°C at a pressure of about 1 kbar. The S, O, and C isotopic compositions of ore-forming fluids that pertain to the second stage of metasomatism (δ34S= +8.5‰, δ18O = +10‰, and δ13C= −11 to −18‰) indicate their crustal origin. The generally similar conditions and products of the ore-forming metasomatic process at the giant Sukhoi Log deposit and at the small Golets Vysochaishy deposit are combined with some differences. The formation of the described deposits was related to the deep convection of fluids along shear zones followed by more local flows of postmagmatic solutions derived from the emplaced granitic magma.

Mass-balance analysis of bulk-rock chemical changes during mylonitization of a megacryst-bearing granitoid, Cheongsan shear zone, Korea

Deformation of a megacryst-bearing granitoid pluton has produced a ∼100 m-thick shear zone (viz., Cheongsan shear zone of South Korea) from protomylonite to muscovite-rich ultramylonite, showing variations in microstructural and mineralogical characteristics along the pluton margin. Petrographic observations within the shear zone suggest evidence for various syntectonic K-feldspar and plagioclase (feldspars hereafter) breakdown and muscovite formation through chemical reactions during mylonitization. Megacrysts up to 15 cm long make it difficult to have representative samples for chemical analysis. Here, we have used a mass-balance analysis (i.e., ‘best-fit’ Al–Ti–Fe isocon) for inferring the changes in major element chemistry during the mylonitization of megacryst-bearing granite. The results show variations in alkalies and silica, reflecting concentration changes (loss or gain) by fluid-assisted mass transfer and the role of SiO 2-rich fluids during progressive development from protolith to ultramylonite of the Cheongsan shear zone. Various bulk-rock volume-changes from 8% loss to 13% gain are calculated relative to the ‘best-fit’ Al–Ti–Fe isocon. Although comparison of the calculated protolith and observed mylonite compositions using ‘best-fit’ isocon analysis may result in uncertainties in interpretation, the present results are consistent with petrographic observations, indicating the element mobility, fluid-assisted mass transfer and the role of SiO 2-rich fluids during progressive development of the Cheongsan shear zone.

White mica domain formation: A model for paragonite, margarite, and muscovite formation during prograde metamorphism

Scanning transmission electron microscopy images of the 00l white mica planes in crystals from central Switzerland and Crete, Greece, reveal that domains of paragonite, margarite, and muscovite are ordered within the basal plane. Energy dispersive X-ray analyses show that both cations in the interlayer and in the 2:1 layer have ordered on the scale of tens to hundreds of nanometers. Domain boundaries can be both sharp and crystallographically controlled or diffuse and irregular. A model outlining the domain formation process is presented that is consistent with X-ray powder diffraction and transmission electron microscopy data. The domain model incorporates aspects of a mixedlayered and a disordered compositionally intermediate phase models. The main feature of the model is the formation of mica species that segregate within the basal plane and contradict the notion of homogeneous layers within mixed-layer phases. Implications for the formation of all diagenetic and very low-grade metamorphic 2:1 sheet silicates are discussed

Wall-rock metasomatism of carbonaceous terrigenous rocks in the Lena gold district

The Lena gold district is situated in the fold-and-shear belt of the southern framework of the Siberian Platform. The gold deposits are hosted in the Riphean-Vendian Khomolkho and Aunakit formations, revealing the strict control of ore mineralization by folding and shearing. The microstructure of metasomatically altered ore-bearing carbonaceous sedimentary rocks at the Sukhoi Log, Golets Vysochaishy, and Verninsky deposits (the latter includes the Pervenets vein zone) testifies to parallelism in the development of shearing, foliation, and ore-forming metasomatism. The local pressure gradients are marked by removal of silica from pressured zones into opened cleavage fractures and pockets. Two metasomatic stages are recognized: (1) early sodic metasomatism, which is characterized by the assemblage of magnesian siderite and paragonite, and (2) late potassic metasomatism, with formation of muscovite in association with sideroplesite and ankerite. The rocks altered at the early stage are distinguished by elevated Ni, Cr, and probably PGE contents. The second stage, close in age to the emplacement of Hercynian granitic plutons, was accompanied by the gain of chalcophile metals and deposition of the bulk of gold. In mineral composition, the metasomatic rocks are close to beresites, but the alteration differed in somewhat elevated alkalinity, so that microveinlets of albite and potassium feldspar occur in the ore zone together with muscovite. The ratio of modal muscovite to paragonite contents in orebodies is substantially higher than in the surrounding metasomatized rocks. This ratio directly depends on the degree of rock permeability and the intensity of the flow of ore-forming solutions. Carbonaceous matter (CM) in the ore zone underwent reworking and redeposition. CM is graphitized to a lesser extent than in the rocks affected by regional metamorphism. The spatial distribution of CM containing nitro and amino groups indicates more oxidizing conditions in the zone of ore deposition than at a distance from this zone. The temperature of metasomatic processes estimated from the muscovite, muscovite-paragonite, and chlorite mineral thermometers and fluid inclusions in quartz was 300–350°C at a pressure of about 1 kbar. The S, O, and C isotopic compositions of ore-forming fluids that pertain to the second stage of metasomatism (δ34S= +8.5‰, δ18O = +10‰, and δ13C= −11 to −18‰) indicate their crustal origin. The generally similar conditions and products of the ore-forming metasomatic process at the giant Sukhoi Log deposit and at the small Golets Vysochaishy deposit are combined with some differences. The formation of the described deposits was related to the deep convection of fluids along shear zones followed by more local flows of postmagmatic solutions derived from the emplaced granitic magma.

Weakening of deforming granitic rocks with layer development at middle crust

In the middle crust, deformation of granitic rocks is characterized by crystal plastic deformation of quartz and cataclasis of feldspar. For common granitic rocks with textures of framework feldspar and interstice-filling quartz, brittle strength of feldspar is a close approximation of the bulk rock strength because feldspar forms the load-bearing framework. With deformation, these rocks tend to develop localized high strain zones. The high strain zones commonly consist of quartz-rich layers and feldspar-rich layers. We have examined how the strength of granitic rocks changes with the volume fraction of these layers by combining the flow laws developed by Handy et al. [Handy, M.R., Wissing, S.B., Streit, L.E., 1999. Frictional-viscous flow in mylonite with varied bimineralic composition and its effect on lithospheric strength. Tectonophysics 303, 175–191]. Our results suggest a dramatic weakening of the bulk rock strength at an early stage of the layer development. We also found that formation of muscovite in the layer structures by breakdown of feldspar can result in further weakening in the layer structure. The bulk-rock strength with mica-bearing layers is reduced by a significant amount, compared with the mica-absent layers. Our analysis suggests that layer development with syntectonic formation of mica can be a major source of weakening for granitic rocks.

Thermodynamic analysis of the system Na2O-K2O-CaO-Al2O3-SiO2-H2O-F2O−1: Stability of fluorine-bearing minerals in felsic igneous suites

Thermodynamic analysis of the system Na2O-K2O-CaO-Al2O3-SiO2-H2O-F2O−1 provides phase equilibria and solidus compatibilities of rock-forming silicates and fluorides in evolved granitic systems and associated hydrothermal processes. The interaction of fluorine with aluminosilicate melts and solids corresponds to progressive fluorination of their constituent oxides by the thermodynamic component F2O−1. The chemical potential μ(F2O−1) buffered by reaction of the type: MOn/2 (s)+n/2 [F2O−1]=MFn (s, g) where M=K, Na, Ca, Al, Si, explains the sequential formation of fluorides: carobbiite, villiaumite, fluorite, AlF3, SiF4 as well as the common coexistence of alkali- and alkali-earth fluorides with rock-forming aluminosilicates. Formation of fluorine-bearing minerals first starts in peralkaline silica-undersaturated, proceeds in peraluminous silica-oversaturated compositions and causes progressive destabilization of nepheline, albite and quartz, in favour of villiaumite, cryolite, topaz, chiolite. Additionally, it implies the increase of buffered fluorine solubilities in silicate melts or aqueous fluids from peralkaline silica-undersaturated to peraluminous silica-oversaturated environments. Subsolidus equilibria reveal several incompatibilities: (i) topaz is unstable with nepheline or villiaumite; (ii) chiolite is not compatible with albite because it only occurs only at very high F2O−1 levels. The stability of topaz, fluorite, cryolite and villiaumite in natural felsic systems is related to their peralkalinity (peraluminosity), calcia and silica activity, and linked by corresponding chemical potentials to rock-forming mineral buffers. Villiaumite is stable in strongly peralkaline and Ca-poor compositions (An 5) saturate with topaz or fluorite. Crystallization of topaz is restricted to peraluminous conditions, consistent with the presence of Li-micas or anhydrous aluminosilicates (cordierite, garnet, andalusite). Fluorite is predicted to be stable in peraluminous biotite granites, amphibole-, clinopyroxene- or titanite-bearing calc-alkaline suites as well as in peralkaline granitic and syenitic rocks. Fluorine concentrations in felsic melts buffered by the coexistence of F-bearing minerals and feldspars increase from peralkaline through metaluminous to mildly peraluminous compositions. At low-temperature conditions, the hydrothermal evolution of peraluminous granitic and greisen systems is controlled by white mica-feldspar-fluoride equilibria. With decreasing temperature, topaz gradually breaks down via: (i) (OH)F−1 substitution and fluorine transfer to fluorite by decalcification of plagioclase below 600 °C, (ii) formation of muscovite and additional fluorite at 475–315 °C, and (iii) formation of paragonite and cryolite, consuming F-rich topaz and albite below 315 °C. These equilibria explain the absence of magmatic fluorite in Ca-bearing topaz granitic rocks; its abundance in hydrothermal rocks is due to: (i) closed-system defluorination of topaz, (ii) open-system decalcification of plagioclase or (iii) hydrolytic alteration. These results provide a complete framework for the investigation of fluorine-bearing mineral stabilities in felsic igneous suites.

Hydrothermal alteration and geochemical dispersion in the regolith at Panglo, Eastern Goldfields, Western Australia

Cuttings from 22 holes drilled through steeply dipping, weathered shales and volcanics at Panglo, 30 km N of Kalgoorlie, help define mineralogical and geochemical variations around flat-lying supergene Au mineralization within a stripped lateritic profile. The regolith profile contains very saline groundwaters only a few metres below the suface. Ore occurs in saprolite and saprock, below a mottled zone which is generally unconformably overlain by c. 0.5 m of fluvial/colluvial sediments. Apart from some surface enrichment associated with pedogenic carbonate, Au is strongly depleted in the saprolite above the supergene ore horizon, and only subeconomic mineralization occurs in the underlying fresh rocks. The Au mineralization at depth is accompanied by pyrite and elevated Ag, As, Co, Cu, Sn, W and Zn contents and is associated with the destruction of albite and formation of muscovite. In the regolith, supergene Au ore at Panglo occurs in the basal portion of the saprolite and Au maintains its association with these elements because they are incorporated into secondary oxide minerals. These elements are thus useful pathfinders for Au, especially as some (e.g. As and Cu) form substantial dispersion haloes about ore. Although the ore is oxidized, it is still within its original primary hydrothermal alteration zone, characterized by muscovite and peripheral paragonite development, especially in shale sequences. Because these micas are resistant to weathering, their distributions can be readily mapped in the regolith. Alternatively, elevated K and depleted Na, Ba and Sr can be used as lithogeochemical indicators of mineralization in weathered shales. Use of Na in alteration indices is complicated by its presence in halite at Panglo, but K/Ba ratios do identify the relict zones of hydrothermal alteration within the regolith.

Lithium-Bearing Donbassite and Tosudite from Echassières, Massif Central, France

AbstractLithium-bearing donbassite and tosudite were found in veins in hydrothermally altered granite (Beauvoir granite) in the northern part of the Massif Central, France. The two minerals are characterized by their high Li contents and low Mg and Fe contents; their structural formulae are: $${\left( {S{i_{3.81}}A{l_{0.19}}} \right)_{\Sigma = 4.00}}{O_{10}}{\left( {A{l_{3.81}}L{i_{0.52}}Fe_{0.01}^{2 + }C{a_{0.02}}M{g_{0.01}}} \right)_{\Sigma - 4.38}}{\left( {OH} \right)_8}{\left( {N{a_{0.07}}{K_{0.04}}} \right)_{\Sigma = 0.11}}$$ for donbassite and $${\left( {S{i_{3.50}}A{l_{0.50}}} \right)_{\Sigma = 4.00}}{O_{10}}{\left( {A{l_{2.95}}L{i_{0.22}}Fe_{0.01}^{3 + }T{i_{0.01}}} \right)_{\Sigma = 3.19}}{\left( {OH} \right)_5}{\left( {C{a_{0.01}}N{a_{0.15}}{K_{0.18}}} \right)_{\Sigma = 0.34}}$$ for tosudite.These chemical compositions indicate that the donbassite is an intermediate member of the donbassite-cookeite solid solution series and that the tosudite consists of interstratified Li-donbassite and beidellite. Both Li-bearing minerals show thermal behavior distinct from those previously reported for dioctahedral chlorite and tosudite.Petrographie investigation of drill cuttings from the Echassières area indicates that the two minerals were formed in an intermediate stage of hydrothermal alteration following an early stage characterized by formation of muscovite (2M1) at &gt;350°C and before the latest stage characterized by deposition of kaolinite and randomly interstratified illite/smectite at &lt; 100°C. Moreover, tosudite occurs in the upper part of the granite, whereas donbassite is restricted to the lower part, suggesting the formation of tosudite at lower temperatures.

A Critical Evaluation of the Heats of Formation of Zoisite, Muscovite, Anorthite, and Orthoclase

The heats of formation of zoisite, muscovite, and anorthite were determined by acid-solution calorimetry in a mixture of 20 per cent HC1-5 per cent HF. A new method of correcting the measured heats of solution for impurities is developed. This method is used to correct both the author's measurements and the heats of formation of muscovite, anorthite, and orthoclase measured by previous workers. The new correction method results in much better agreement between all the heats of formation. The values obtained are used to calculate the univariant equilibrium curves for the following reactions; (1) Mu = Or + Cn + V, (2) Mu + Qz = Or + Sil + V, and (3) 2 Zo + Sil + Qz = 4 An + V. These curves are compared with curves obtained by direct experiment.

Formation of muscovite in soils

Formation of muscovite in soils