Muscovite Structure Research Articles

Medium-temperature calcination and acid pressure leaching extract the Al2O3 from coal gangue: activation mechanism and kinetic analysis.

Bauxite is an important strategic resource, and it is facing with the problem of balance between high demand of bauxite ore and low resource of bauxite reserves in China. This research takes the Fuxin coal gangue as the object and extracts Al2O3 by medium-temperature calcination and acid pressure leaching process. The results show that at a calcination temperature of 650 °C, calcination time of 2 h, acid pressure leaching temperature of 160 °C and acid pressure leaching time of 6 h, the extraction ratio of Al2O3 reaches 80.19%. Furthermore, the research finding that the complete activation temperatures of kaolinite and muscovite are 650 °C and 850 °C, respectively, and the decomposition reactions of active Si, active Al, and metakaolinite occur above 800 °C, which leads to a low extraction ratio of Al2O3. The acid pressure leaching process can directly destroy the muscovite structure at a calcination temperature of 650 °C. The acid pressure leaching kinetic equations are studied by three kinetic models, and the apparent activation energies of the reactions are calculated by the Arrhenius formula. The results show that acid pressure leaching is subject to solid residue in-layer diffusion control, and the kinetic equation is "". The apparent activation energy is 13.48 kJ mol-1.

Novel intercalation mechanism of cationic surfactants modified muscovite

Intercalation of cationic surfactants cetyltrimethylammonium bromide (CTAB) into the interlayer space of muscovite by the ion-exchange process was investigated. Changes in the surface and structure of the muscovite modified with CTAB were characterized using Wide angle X-ray diffraction (WAXD), Fourier-transform infrared spectroscopy (FTIR) and Transmission electron microscopy (TEM). As revealed by WAXD results, the basal spacing of CTAB-muscovite increased from 0.99 nm to 2.82 nm, indicating the formation of an intercalated structure. Through this intercalated structure, the CTA+ ions in the muscovite interlayer space were arranged in a paraffin complex that may ease the process of intercalation within the polymer matrices. FTIR spectra indicated new absorption bands at 2922 and 2855 cm−1, which signified the presence of a long alkyl chain, verifying the incorporation of CTAB into the muscovite structure. The TEM images showed separation within the muscovite layers was more intense, given their flat morphology. These micrographs demonstrate that CTAB addition had expanded the basal spacing in the muscovite layers. The present study concludes that the intercalation of CTAB-modified muscovite has a potential for polymer intercalation that can be tailored to a specific purpose.

Microwave Versus Conventional Porcelain Firing: Greenware to Biscuit Crystallochemical Transformations

Abstract This work reports and compares the structural crystallochemical transformations occurring during the microwave and conventional porcelain manufacture. Batches of greenware (just dried) porcelain pieces are microwave and electrically fired at increasing temperatures, from 420 °C up to 1100 °C. Crystallochemical transformations are identified by X-ray diffraction (XRD) analysis and compared the results from samples microwave and conventionally fired. Microwave fired samples show the full and rapid collapse of kaolinite structure for firing temperatures just above 500 °C, whereas the collapse of kaolinite structure of the electrically fired samples is progressive, from about 500 °C up to 950 °C. Muscovite structure totally collapses at about 950 °C for microwave fired greenware samples, whereas muscovite structure total collapse only occurs at about 1050 °C for electrically fired greenware samples. Microwave and electric firing lead to appreciable differences in the sanidine–orthoclase–microcline structural transformations. Mullite formation could be identified in the microwave fired samples at temperatures 50 °C lower than in the electrically fired ones, especially for the conventional firing temperatures above 1050 °C, the same temperature reported in the literature.

Optimization of Oxidative Leaching for Vanadium Extraction from Low-Grade Stone Coal Using Response Surface Methodology

The feasibility and kinetics of vanadium (V) recovery from oxidative leaching of low-grade stone coal using MnO2 were investigated. Oxidative leaching processes (OLPs) were designed using response surface methodology (RSM) based on the central composite design (CCD) model. The results show that the order of factors that influence OLPs is leaching temperature > H2SO4 concentration > leaching time > MnO2 dosage. The interaction between leaching temperature and H2SO4 concentration on the OLP is the most significant. Vanadium leaching efficiency was 89.3% using 31% H2SO4 and 3% MnO2 at 90 °C for 7.9 h. The kinetics of V leaching from stone coal show that the leaching rate is controlled by chemical reaction through a layer according to the shrinking core model and the activation energy is 55.62 kJ/mol. A comparison of the SEM-EDS results of minerals before and after leaching confirms that the muscovite structure was significantly destroyed and V and aluminum (Al) were effectively dissolved during the OLP.

Function of Interface Deposition of Calcium Sulfate in Pressure Acid Leaching of Black Shale-Hosted Vanadium

During pressure acid leaching process of black shale-hosted vanadium, increasing the reaction interface of muscovite dissolution can enhance the vanadium release. In this paper, calcium sulfate (CaSO4) deposition behavior and its effect on muscovite under K2SO4 assistance were focused on for demonstrating the function of CaSO4 on vanadium leaching from the black shale. Results showed that as K2SO4 mediated, the apparent activation energy of vanadium leaching and the apparent reaction order of sulfuric acid decreased from 24.37 kJ/mol to 16.63 kJ/mol and 2.7 to 1.9, respectively. The leaching rate and dependence on pH value were modified. The vanadium leaching acceleration owed to CaSO4 deposition on muscovite in the black shale. The ion absorption stimulations found that Ca2+ is confirmed to be easily absorbed on the six-membered ring cavity of silicon-oxygen tetrahedrons in muscovite structure prior to K+ and Na+. Meanwhile, SO42− provides two oxygen atoms to bond with Ca2+ absorbed on muscovite (001) surface. The continuous absorption and bonding create CaSO4 deposition on muscovite (001) surface which also involves the load transmitting. The stress load transmitting correlates to pore formation in muscovite particles. It was proved that massive micropores initiated and proliferated in the existing pores under K2SO4 assistance. The porosity caused by CaSO4 deposition greatly increased the reaction interface of muscovite dissolution and accelerate internal diffusion of H+ to the reaction interface, which can significantly weaken the vanadium leaching dependence on acid.

Mechano-Chemical Processing of Diaspore Sample for Extraction and Synthesis of Gamma-Alumina and Potash Values

In this study, a diaspore sample is evaluated as a dual source of alumina and potash. The thermal treatment of diaspore with sodium hydroxide yielded alumina and potash values. Microwave heating resulted in enhanced diffusion with improved precipitate purity and recovery with a significant reduction in reaction time. The thermal treatment precipitate comprises alumina purity of 48% with a recovery of 49%. The mechanical milling route yields optimal conditions of 8 h milling followed by acid leaching in 2 M HCl at 50°C for 1 h with ~ 70% and 45% potash and alumina extraction, respectively. The dissociation of the muscovite structure is crucial for high extraction values, and milling time was found to be the significant factor. The milling route at optimal conditions yielded an alumina precipitate with ~ 89% purity with a surface area of 104.6 m2/g and a sylvinite-rich solution, which can be used in fertilizer application.

Direct Observation of the Orientational Anisotropy of Buried Hydroxyl Groups inside Muscovite Mica.

Muscovite mica (001) is a widely used model surface for controlling molecular assembly and a common substrate for environmental adsorption processes. The mica (001) surface displays near-trigonal symmetry, but many molecular adsorbates-including water-exhibit unequal probabilities of alignment along its three nominally equivalent lattice directions. Buried hydroxyl groups within the muscovite structure are speculated to be responsible, but direct evidence is lacking. Here, we utilize vibrational sum frequency generation spectroscopy (vSFG) to characterize the orientation and hydrogen-bonding environment of near-surface hydroxyls inside mica. Multiple distinct peaks are detected in the O-H stretch region, which we attribute to Si/Al substitution in the SiO4 tetrahedron and K+ ion adsorption above the hydroxyls based on density functional theory simulations. Our findings demonstrate that vSFG can identify the absolute orientation of -OH groups and, hence, the surface termination at a mica surface, providing a means to investigate how -OH groups influence molecular adsorption and better understand mica stacking-sequences and physical behavior.

Effect of CaF2/CaO Composite Additive on Roasting of Vanadium-Bearing Stone Coal and Acid Leaching Kinetics

In this paper, the composite additive of CaF2/CaO was used to extract vanadium from stone coal, and the effect of roasting and leaching kinetics were studied. The purpose of this manuscript is to realize and improve the vanadium recovery from stone coal using the composite additive. The experimental results indicated that the roasted clinker can be obtained under the conditions of CaF2/CaO at a mass ratio of 2:3 and a total additive amount of 10 wt %, a roasting temperature 850 °C, and a roasting time of 90 min. The leaching rate of vanadium can reach 86.74%, which increased by 16.4% compared with that of blank roasting under the conditions including a leaching temperature of 950 °C, a sulfuric acid concentration of 15% (v/v), a leaching time of 2 h, and a ratio of liquid to solid of 3 mL/g. The phase transformation analysis indicated that the muscovite structure was effectively destroyed during the roasting process comparing with no additives, which provided the basis for vanadium dissociation. Roasting can promote the formation of calcium vanadate, which is beneficial to the leaching of vanadium. The vanadium leaching kinetic analysis indicated that the activation energy of the acid leaching reaction decreased from 42.50 KJ/mol in the blank roasting to 22.56 KJ/mol in the calcified roasting, and the reaction order, with respect to the sulfuric acid concentration, decreased from 1.15 to 0.85. Calcified roasting has a better mineral activation than blank roasting, which can accelerate the leaching of vanadium and reduce the dependence on high-temperature and high acid levels in the leaching process.

Effects of hydration and hardening of calcium sulfate on muscovite dissolution during pressure acid leaching of black shale

In the conventional process of oxygen pressure acid leaching of black shale, vanadium extraction depends on acid attack to muscovite, resulting in high acid consumption and a long leaching time. The two problems significantly reduce equipment life, increase production costs, and decrease production efficiency. To solve these problems, hydration and hardening of calcium sulfate were introduced to promote muscovite cracking, increasing the exchange reaction rate of hydrogen ion to aluminum ion. This paper investigated the effect of hydration and hardening of calcium sulfate on calcium sulfate growth and muscovite dissolution, exploring interactions between calcium sulfate and muscovite. Results indicate that in stress-damaged muscovite structure, propagation of ductile cracks in muscovite particles increases their specific surface area and weakens muscovite structural strength. These effects allow muscovite to dissolve much more easily during the pressure acid leaching process. The hydration and hardening of calcium sulfate crystals can thus facilitate muscovite dissolution.

Comparison of microwave and conventional blank roasting and of their effects on vanadium oxidation in stone coal

ABSTRACTThe oxidation behaviour of vanadium in stone coal and its mechanisms in conventional blank roasting (CBR) and microwave blank roasting (MBR) are investigated. In both roasting methods, vanadium oxidation rates are increased and the controlling step of vanadium oxidation reaction is changed from chemical control to internal diffusion control with increasing temperature. Compared to CBR, MBR was more efficient in vanadium oxidation under same roasting conditions. The change of controlling step occurred at the temperature range of 500–600 °C and 600–700 °C for MBR and CBR, respectively. This oxidation behaviour of vanadium was mainly dependent on the reducing materials in stone coal and their reaction characteristics. Due to efficient and the lower temperatures of mineral transformations (including reaction of reducing materials and deformation of muscovite structure), MBR had higher vanadium oxidation efficiency and lower temperature range of changing the controlling step than CBR.

Comparison of the mechanisms of microwave roasting and conventional roasting and of their effects on vanadium extraction from stone coal

Experiments comparing microwave blank roasting and conventional blank roasting for typical vanadium-bearing stone coal from Hubei Province in central China, in which vanadium is present in muscovite, were conducted to investigate the effects of roasting temperature, roasting time, H2SO4 concentration, and leaching time on vanadium extraction. The results show that the vanadium leaching efficiency is 84% when the sample is roasted at 800°C for 30 min by microwave irradiation and the H2SO4 concentration, liquid/solid ratio, leaching temperature, and leaching time are set as 20vol%, 1.5:1 mL·g−1, 95°C, and 8 h, respectively. However, the vanadium leaching efficiency achieved for the sample subjected to conventional roasting at 900°C for 60 min is just 71% under the same leaching conditions. Scanning electron microscopy (SEM) analysis shows that the microwave roasted samples contain more cracks and that the particles are more porous compared to the conventionally roasted samples. According to the results of X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) analyses, neither of these roasting methods could completely destroy the mica lattice structure under the experimental conditions; however, both methods deformed the muscovite structure and facilitated the leaching process. Comparing with conventional roasting, microwave roasting causes a greater deformation of the mineral structure at a lower temperature for a shorter roasting time.

Hydrogen-bond and cation partitioning in muscovite: A single-crystal neutron-diffraction study at 295 and 20 K

The crystal chemistry of a pegmatitic Fe-bearing muscovite (with FeO ~5.1 wt%) from Val di Crana, Arvogno (Verbania, Nothern Italy) has been investigated by means of wavelength-dispersive X-ray spectroscopy and constant-wavelength [λ = 0.9462(2) Å] single-crystal neutron diffraction at 295 and 20 K (2θmax = 90°). The structure refinement at 295 K shows no significant deviation from the full occupancy of the K site (using the scattering length of potassium alone), and a disordered Si/Aldistribution in the two independent tetrahedral sites (i.e., T1 and T2) and Fe/Al-distribution in the M2 octahedral site. The difference Fourier map of the nuclear density shows that only one independent H site occurs in the muscovite structure, at both room and low temperature. No evidence of disorder in two sub-sites, as observed in a previous study, was found. The thermal displacement of the H site is here described anisotropically. A trifurcated hydrogen bonding scheme was found: the O6-H bond distance corrected for “riding motion” is ~0.984 Å at 295 K, and three significantly weak hydrogen bonds to the O atoms O2, O4, and O6 occur, with H···O2 = 2.635(5), H···O4 = 2.657(4), and H···O5 = 2.647(4) Å and O6-H···O angles all similar in value (~138°). The structure refinements show that the structure configuration of muscovite is maintained at least down to 20 K: the cation disordering in the tetrahedral and octahedral site and the H-bonding scheme are preserved. The structural evolution induced by decreasing temperature is governed by the contraction along a direction perpendicular to (001), mainly due to the compression of the “inner” K-O bonds, which leads to an increase of the tetrahedral rotation angle (α) of the six-membered ring. A further effect in response to lowering the temperature is a significant reduction of the magnitude of the thermal displacement parameters.

An experimental study of the dissolution mechanism and rates of muscovite

Steady-state muscovite dissolution rates have been measured at temperatures from 60 to 201 °C and 1 ⩽ pH ⩽ 10.3 as a function of reactive solution K, Si, and Al concentration. The pegmatitic muscovite used in these experiments has a composition consistent with (Na 0.09, K 0.86)Fe 0.05Al 2.92Si 3.05O 10(OH 1.95, F 0.06). All experiments were performed in titanium mixed-flow reactors. All experiments were performed at far-from-equilibrium conditions with respect to muscovite. All reactive solutions were undersaturated with respect to secondary product phases other than for some experiments which were supersaturated with respect to bohemite and diaspore; steady-state dissolution was stoichiometric for all experiments that were undersaturated with respect to these phases. The variation of rates with reactive solution composition depends on the solution pH. At pH ⩽ 7 rates were found to decrease significantly with increasing reactive fluid Al activity but be independent of aqueous SiO 2 activity. pH < 7 rates measured in the present study from 60 to 175 °C are consistent with r + ,K-muscovite,pH < 7 ( mol/cm 2 / s ) = 10 - 6.53 - exp - 58.2 kJ / mol RT a H + 3 a Al 3 + 0.50 where r + refers to the far-from-equilibrium muscovite dissolution rate, R designates the gas constant, T signifies absolute temperature and a i represents the activity of the subscripted aqueous species. In contrast at basic pH muscovite dissolution rates depend on both reactive fluid Al and Si activity consistent with r + ,muscovite, 150 ° C, 8.5 > pH > 10.5 mol/cm 2 / s = 10 - 9.195 - exp - 89.1 kJ/mol RT a H + 3 a Al 3 + 0.5 a SiO 2 - 1 These contrasting behaviors suggest a change in dissolution mechanism with pH. At acidic pH rates appear to be controlled by the breaking of tetrahedral Si–O bonds after adjoining tetrahedral Al have been removed by proton exchange reaction. At basic pH rates may be controlled by the breaking of octahedral Al–O bonds after adjoining tetrahedral Al and Si have been removed from the muscovite structure.

Nickel-rich chromian muscovite from the Indus suture ophiolite, NW Pakistan: Implications for emerald genesis and exploration

Ubiquitous veins and stockworks of quartz traverse the ophiolitic emerald-hosting, carbonate-altered ultramafic rocks in the Swat Valley. Some of the emerald-bearing quartz veins contain chromian muscovite and tourmaline. In addition, veins and clusters consisting of chromian muscovite and/or tourmaline occur in zones of carbonate-altered rocks where the quartz veins are most abundant. The chromian muscovite is characterized by high Mg/Fe ratios (4‐9) and contains variable and in some cases anomalously high concentration of Ni (ranging up to 9 wt% NiO). A detailed investigation reveals that the Ni and Mg entered the chromian muscovite structure as a part of a complex coupled substitution: (Fe VI , Mn VI , Mg VI , Ni VI ) 2+ + [Si IV ] 4+ ↔ (Al VI , Cr VI ) 3+ + [Al IV ] 3+ . The stable coexistence of quartz, chromian muscovite, tourmaline and emerald suggests that all these phases are cogenetic and precipitated from Si-rich, Al-, Be-, B- and K-bearing fluids related to a single episode of hydrothermal activity. The Mg, Cr and Ni contents in chromian muscovite were most probably extracted by the percolating hydrothermal solutions from the host carbonate-altered ultramafic rocks through wall rock reaction. The observed high variability in the Mg, Cr and Ni contents of chromian muscovite probably reflects low mobility of these elements during the hydrothermal process or a result of local equilibrium under relatively low T conditions.

The CS/K Exchange in Muscovite Interlayers: An Ab Initio Treatment

AbstractPlane-wave pseudopotential total energy calculations have been applied to investigate the structure and energetics of the Cs/K exchange into interlayer sites in muscovite mica. Novel muscovite structures were designed to isolate the effects of 2:1 layer charge, cation size/interlayer site shape, and tetrahedral Al/Si substitutions on the exchange. All atom and cell-parameter optimizations were performed with the intention to mimic the constant pressure, non-isovolumetric exchange conditions thought to be found at frayed-edge sites. Under conditions where the cell parameters are allowed to relax, the overall Cs/K exchange reaction is surprisingly close to isoenergetic. The forward reaction is more strongly favored with increasing layer charge. For the condition of zero layer charge and no interlayer site distortion, the difference in the optimal interlayer spacing for Cs relative to K is very small, indicating a baseline indifference of the muscovite structure to cation size. The presence of 2:1 layer charge or tetrahedral rotations arising from Al/Si substitutions clearly change this outcome. Analysis of the dependence of the interlayer spacing on layer charge shows that while the spacing collapses with increasing layer charge for K as the interlayer cation, the reverse is true for Cs. We attribute the contrasting behavior to inherent differences in the ability of these cations to screen 2:1 layer-layer repulsions. Such effects might be involved during exchange at frayed-edge sites where interlayer spacings are increased. This is known, from experiment, to be very selective for Cs. Overall, the exchange energetics are so low that the Cs/K exchange rate and degree of irreversibility are likely to be dominated by diffusion kinetics.

Vibrational analysis of the dioctahedral mica; 2M1muscovite

Raman spectra and lattice dynamics calculations are presented for the dioctahedral mica, muscovite. Calculated fundamental mode frequencies for the Raman-active and A g and B g species were fit to observed fundamentals assigned to features in the two polarized Raman spectra collected, so that unambiguous vibrational assignments could be made to most peaks in the Raman data. Calculated frequencies for the IR-active A u and B u modes generally fall within the frequency ranges of bands in the IR spectra for muscovite presented earlier. Factor group analysis indicates that motion from all atom types in the muscovite structure can be found in modes for all four vibrational species. Force constant values determined for muscovite are similar to equivalent values calculated for the trioctahedral mica, phlogopite. Raman and IR-active modes calculated at frequencies greater than 800 cm -1 are dominated by internal sheet T-O stretch and T-O-T bend motions, where T is a tetrahedral site. Modes between 800 and 360 cm -1 have internal tetrahedral sheet motions mixed with K and octahedral Al displacements. Modes at frequencies less than 360 cm -1 have lattice and OH motions. Inter-sheet bonding in the muscovite structure is strong enough to affect modes at frequencies as high as 824 cm -1 .

The Effect of the Instability of Muscovite During In Vacuo Heating on 40Ar/ 39Ar Step-Heating Spectra

The goal of this study was to ascertain the nature of the Ar release mechanism(s) for a single, well characterized muscovite heated incrementally in vacuo: (1) at temperatures and time intervals typical of 40Ar/ 39Ar step heating experiments and (2) isothermally at 500°C and 700°C for time intervals much longer than typical 40Ar/ 39Ar experiments. The rate of delamination was monitored by SEM, and the rate of dehydroxylation was determined by XRD analyses. The rate of in vacuo Ar loss was compared to that for muscovite heated at 700°C and 2 kbar H 2O pressure. For all experiments, the rate of Ar loss was found to be consistent with the rates of dehydroxylation and delamination. At 500°C, Ar loss behavior for a 3000 μm diameter muscovite grain was approximated by volume diffusion, but the Ar release pattern became increasingly non-Fickian with decreasing grain size. We propose that the cause of the non-Fickian behavior is delamination. The portions of the isothermal runs exhibiting diffusion-like profiles also yielded discordant 40Ar/ 39Ar ages and low atmospheric Ar contamination. We attribute this phenomenon to the preferential concentration of atmospheric Ar in interlayer extended defects and of 40Ar∗ in interlayer vacancies, whereas 39Ar is uniformly distributed throughout the muscovite structure by recoil. The 40Ar/ 39Ar age spectrum of the muscovite heated under hydrothermal conditions has a staircase shape, comparable to that usually interpreted as due to 40Ar∗ diffusive loss, whereas 40Ar/ 39Ar laser spot analyses did not allow this interpretation. The in vacuo Ar release rate for this sample, however, indicates that it had been altered during the experiment. Therefore, we propose that this 40Ar/ 39Ar age spectrum reflects the differential release of Ar from the alteration phases vs. muscovite. For our sample, dehydroxylation and delamination control the in vacuo Ar release at temperatures less than 900°C, whereas Ar diffusion from thin dehydroxylated slabs may dominate the Ar release mechanism for temperatures greater than 900°C. This model would predict that the recovery of fossil 40Ar∗ concentration gradients from muscovite by typical incremental heating schedules is not possible. The rates of delamination in vacuo and the rate of Ar diffusion for muscovite in nature, however, both depend upon its the chemical composition, structural integrity, and grain size. Consequently, for samples with either a naturally occurring broad range of grain sizes, such as detrital muscovite and authigenic clay from sedimentary rocks, or a compositionally or structurally heterogeneous population of grains, such as muscovite from shear zones, 40Ar/ 39Ar incremental heating may be able to detect intergranular variations in the K/Ar age.

Grinding of muscovite: influence of the grinding medium

Muscovite was ground in water, alkaline chloride solutions, methanol and toluene. The influence of the grinding medium was investigated using several methods, in particular by electron microscopy. It was found that the addition of lithium ions in aqueous media or NH3 to methanol facilitates the breakdown of the muscovite structure. The results are explained supposing that water or methanol form lubricating films on the mineral surface, the lubricating properties of both liquids being lost when a hydrogen-bond disrupting agent (Li+, NH3) is present in the grinding medium.

Hydroxyl Orientation in Muscovite as Indicated by Electrostatic Energy Calculations

The electrostatic energy of the 2M(1) muscovite structure, KAl(2)(Si(3)Al)- O(10)(OH)(2), has been calculated as a function of the orientation of the hydroxyl group (O-H distance = 0.97 angstrom). The minimum in the electrostatic energy occurs when the OH bond makes an angle of 18 degrees with the cleavage plane and an angle of 31 degrees with the b-axis (in the a-b plane), which is 2.5 degrees away from the orientation of the transition moment as determined from infrared measurements on single crystals. If the K+ ion is excluded from the calculation, the O-H bond makes an angle of 53 degrees with the cleavage plane. This indicates the strong influence that the interlayer cation exerts on the hydroxyl hydrogen in mica structures.

Epitaxial Growth of Ice Crystals on the Muscovite Cleavage Plane and Their Relation to Partial Dislocations

The arrangement of oxygen atoms in hexagonal rings in crystals of ice and muscovite gives two possible alternatives of epitaxial connection between these two structures. Which one of these two alternatives is favored depends entirely on the location of potassium atoms in the cleavage plane of the muscovite structure. Since potassium atoms are displaced from the normal environment by the slip taking place along partial Burgers vectors, epitaxial growth of ice crystals on muscovite can be used for the determination of the slip directions and hence for the study of partial dislocations in muscovite crystals.