Mica Content Research Articles

Hydrothermal mica deposits in altered meta-ultrabasites from north-central Sri Lanka

Extensive vein-type mica deposits at Elahera in north-central Sri Lanka are associated with meta-ultrabasite (MUB) boudins in impure marbles. Mineralization occurs as discontinuous, lenticular bodies concordant with the impure marbles at the contacts with MUB. Impure marbles show typical granulite facies assemblages overprinted by retrograde minerals. The original assemblages of MUBs have been texturally and mineralogically replaced completely, but the alteration did not progress into impure marble country rocks. The alteration products are mainly phlogopite with minor tremolite, calcite and quartz. The micas have likely been formed as a result of the breakdown of diopside in the MUBs. Rock textures and chemical data of whole rocks and minerals suggest that the alteration is due to infiltration of external hydrothermal fluid through the contacts of MUB boudinage layer and impure marbles. The calcium, magnesium and CO2 required for formation of alteration minerals may have been acquired from the host rock, whereas silica, K, Cl and Al were externally derived and transported with the fluid. The most likely source of hydrothermal fluid is exsolved fluid from nearby granitic pegmatites, based on field relations showing preferred contents of mica near pegmatite contacts.

Sedimentology and Ichnology of Late Oligocene Delta Front Reservoir Sandstone Deposit, Greater Ughelli Depobelt, Niger Delta

Sedimentological and ichnological study of cored reservoir sands correlated with wireline logs between two wells, 0.8 km distance apart along dip direction, enabled vertical and cross sectional facies variability assessment aimed at determining intra sand-body continuity in longitudinal or down-dip direction; and sub-environments of deposition and factors that controlled depositional processes. Ten lithofacies described 62 meters cores of the reservoir sands and seals. Sub-environments of deposition identified with lithofacies associations include proximal delta front-mouth bar, distal delta-front, prodelta-offshore, transgressive marine sandstone and tidal flat. High mica content, poor sorting, very coarse quartz grains, high angle bedding contact, micro-slump folds and absent to sparse bioturbation at the base of an upward-coarsening sequence indicated mouth bar deposition and direct link to a distributary channel. The study of vertical and lateral intra-reservoir depositional trends indicated that sediment structural and textural (grain sizes and biogenic features) heterogeneities in the deltaic deposit were controlled by variations in physical energy and mixed interactions of seal level changes, tide, wave, fluvial influx, storm, food supply and oxygen levels. Consequently, there is down-dip lithofacies heterogeneity, pinch out of lithofacies or gradation from coarse grains to finer grains and better sorting. Though ichnodiversity is fairly uniform between the two wells, ichno-abundance and burrow sizes decrease down-dip especially at the proximal delta front-mouth bar deposit. The results of this study improve our knowledge of the characteristics of a mouth bar deposit in a mixed-processes deltaic environment and it can be applied in the characterization of delta front deposit elsewhere with similar depositional processes and tectonic setting.

Spectral gamma-ray logging of the Grès d'Annot, SE France: An outcrop analogue to geophysical facies mapping and well-log correlation of sand-rich turbidite reservoirs

Spectral gamma-ray (GRS) logging is a powerful tool in cyclo- and sequence stratigraphy of carbonate depositional systems. In siliciclastic systems with low chemical maturity, the multi-component character of sediment complicates the interpretation of such logs. This work focuses on understand better the relationships between GRS logs and siliciclastic facies stacking patterns, using GRS measurements combined with lithology, modal composition and geochemistry. This study is focused on outcrops in the St. Antonin–Annot–Grand Coyer–Chalufy areas of the Oligocene Grès d´Annot Formation (SE France).The studied siliciclastics reveal moderately high total radioactivity and mean concentrations of K: 3.8 %, U: 4.5 ppm and Th: 13 ppm. U and Th are predominantly contained within heavy minerals and so tend to be concentrated in mudstones and heterolithic sand-mud facies whereas sandstone and conglomerate facies have slightly higher levels of K due to higher contents of K-feldspars and micas. The abundance of minerals containing radioactive elements and the relatively low compositional contrast between different facies are considered the main reasons why the standard gamma-ray measurements provide only a limited proxy for lithology in this case.Two complete regressive-to-transgressive cycles were identified based on combined Th and Th/K logs and facies stacking patterns. The cycle boundaries are marked by shifts towards coarse-grained facies, abrupt increase of U and Th concentrations and Th/K ratio within the proximal deposits at the St. Antonin section. In the distal Chalufy section, the response of the gamma-ray proxies to facies shifts is reversed. These boundaries, interpreted as basal surfaces of forced regression, can be correlated with prominent erosional surfaces at the Annot section. GRS logging is a sensitive method capable of indicating changes of genetic depositional units in sand-rich turbidite systems. However, detailed facies analysis, mineralogy and geochemistry producing the radioactive signal are necessary to correctly interpret such logs.

Effect of Mica Content in Stone Powder of Manufactured Sand on Performance of Cement Mortar

This paper studies the influence on compressive strength, freezing resistance and microstructure of cement mortar with different content of mica in stone powder, in the tests, manufactured sand with high content of mica and natural river sand were mixed with different proportion, and the content of stone powder was the same in mixed sand. Experiment results indicate that, with the increasing of mica content in stone powder, 28d and 60d compressive strength of cement mortar decreases obvious, mass loss rate and strength loss rate with 50 freeze-thaw cycles increase a little. Microstructure of cement mortar with higher content of mica is not compactly by SEM, the internal defects of cement hardened pastes could be increased because of the flake mica which surface is smooth, and it will cause the spread of micro crack.

The Outdoor Aging Properties of Polypropylene/Mica Composite

In this paper, In this paper, polypropylene / mica composites were prepared by blending, using polypropylene (PP) as matrix, mica as filler. In order to study the anti-aging properties of polypropylene / mica composite materials, the above polypropylene / mica composite materials were placed outside to study the influence of natural aging time on the anti-aging properties and to explore the natural aging mechanism of polypropylene / mica composites. Natural aging research results show that:with the extension of the natural aging time the surface of materials will appear cracks and sheddings. The trends of tensile strength reduce at first, then increase and then decrease; the notched impact toughness values show fluctuating in the early aging, then an increase following and then decreasing.The increase of mica content are good for maintaining the mechanical properties of PP / mica composite, PP-g-MAH helps to maintain the tensile strength, while toughening POE-g-MAH will weaken the anti-aging properties of polypropylene / mica composite materials.

A study of mica structure and strength properties of polymer materials based on it

The mica microstructure is studied, and its shape and particle sizes are found as dependent on coating technology. Using epoxy and organosilicon polymers, several lots of materials with different contents of mica are prepared and mechanical tests are performed. The optimal amounts of mica wherein the initial strength characteristics are preserved are found. The thicknesses of epoxy and organosilicon polymer wherein high optical decorative properties of mica are preserved are determined.

Alpine oxidation of lithium micas in Permian S-type granites (Gemeric unit, Western Carpathians, Slovakia)

AbstractLithium micas of the zinnwaldite and phengite–Li-phengite series occur as characteristic minerals in Permian Li-F-(P) granites of the western Gemeric unit (Western Carpathians) accompanied by topaz, tourmaline, Nb, Ta, Ti, Sn oxides and aluminophosphates. The calculated Li2O contents of all the mica analysed, together with Rb2O and Cs2O were confirmed by LA-ICP-MS analyses for all the identified micas. Samples from three localities were investigated: two surficial (Surovec, Vrchsúl’ová); and one drill hole (Dlhá dolina). Zinnwaldite (polylithionite) occurs in the upper level of the Dlhá dolina granitic intrusion and in the nearby shallow satellite body of Surovec. The lower level porphyritic granites contain only siderophyllite. The Vrchsúl’ ová micas are closer in composition to Li-annite and siderophyllite. Dioctahedral micas are mostly phengites, although zinnwaldite-bearing granites are rich in late-crystallizing Li-phengite, which extensively replaces earlier zinnwaldite. The secondary Liphengite and phengite are interpreted as products of Alpine metamorphism during Cretaceous burial and subsequent exhumation of the Gemeric unit. Reactions are suggested explaining the formation of Li-phengite by reaction of zinnwaldite with phengite or with muscovite. All mica types were investigated by Mössbauer spectroscopy, which showed high degrees of oxidation (25–50% Fe3+ of total Fe) with the exception of zinnwaldite from Vrchsúl’ová, which may have preserved an original, reduced value of 10%. The metamorphic assemblage present permitted calculation of P-T-X conditions: T = 184°C, P = 320 MPa, with oxidation of siderophyllite to phengite + goethite and fO2 at ΔNN = 4.7, confirming the low-grade conditions of the Alpine metamorphism in agreement with previous estimates.

Mapping Advanced Argillic Alteration at Cuprite, Nevada, Using Imaging Spectroscopy

Mineral maps based on Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data were used to study late Miocene advanced argillic alteration at Cuprite, Nevada. Distributions of Fe-bearing minerals, clays, micas, sulfates, and carbonates were mapped using the Tetracorder spectral-shape matching system. The Al content of white micas increases toward altered areas and near intrusive rocks. Alunite composition varies from pure K to intimate mixtures of Na-K endmembers with subpixel occurrences of huangite, the Ca analogue of alunite. Intimately mixed Na-K alunite marks areas of relatively lower alteration temperature, whereas co-occurring Na-alunite and dickite may delineate relict hydrothermal conduits. The presence of dickite, halloysite, and well-ordered kaolinite, but absence of disordered kaolinite, is consistent with acidic conditions during hydrothermal alteration. Partial lichen cover on opal spectrally mimics chalcedony, limiting its detection to lichen-free areas. Pods of buddingtonite are remnants of initial quartz-adularia-smectite alteration. Thus, spectral maps provide a synoptic view of the surface mineralogy, and define a previously unrecognized early steam-heated hydrothermal event. Faulting and episodes of hydrothermal alteration at Cuprite were intimately linked to upper plate movements above the Silver Peak-Lone Mountain detachment and growth, collapse, and resurgence of the nearby Stonewall Mountain volcanic complex between 8 and 5 Ma. Isotopic dating indicates that hydrothermal activity started at least by 7.61 Ma and ended by about 6.2 Ma. Spectral and stable isotope data suggest that Cuprite is a late Miocene low-sulfidation adularia-sericite type hot spring deposit overprinted by late-stage, steam-heated advanced argillic alteration formed along the margin of the Stonewall Mountain caldera.

Optimal injection parameters for multiple qualities in poly lactic acid/nano mica composites

This study melted and mixed poly lactic acid and nano mica into a new nano composite material for injection molding. The injection parameters for the mixture included the melting time, screw speed, heating plate temperature, nano mica content, melting temperature, nozzle temperature, holding pressure, and injection speed. The quality considerations of the new nano composite material were ultraviolet (UV) absorption rate, far-infrared absorption rate, Rockwell hardness, and flame resistance. This study applied main effect analysis and variance analysis theory of the Taguchi method to analyze the single quality characteristic of the experimental results. The optimal factors and level combination was identified through multi-quality integration using the Analytic Hierarchy Process. After consistent examination and calculation of the total weighting of various parameter levels, as well as the ranking of the parameter levels, the optimal injection parameters were obtained. According to the confirmation experiment results, the Signal-to-Noise ratio of the four qualities for the new nano composite fell within the 95% confidence interval, indicating the experiment was reproducible and reliable. The results indicated that the best qualities for the new nano composite are UV absorption rate at 98.22%, far-infrared absorption rate at 90.53%, Rockwell hardness at 108.07, and the limiting oxygen index for fire resistance rating at 30.

Thermal, mechanical and tribological performance of polymer composites rubbed against polymer composites in application in electrical contact breakers

In this investigation, the thermal, mechanical properties and tribological performance of polyamide 6 composites filled up to 30 wt% mica is studied. The dry friction and wear tests of 30 wt% mica-filled polyamide 6 rubbed against 30 wt% mica-filled polyamide 6 and 30% glass fiber reinforced polyamide 6 polymer composite's discs were carried using a pin-on-disc test rig. Test's conditions were room temperature, applied load values of 20 N, 30 N and 40 N and at 0.5 m/s sliding speed. The results show an announced influence on mica content on the coefficient of friction and specific wear rate values of polyamide 6 composites. The results also show the influence of mica content on the mechanical properties, glassy transient temperature Tg and the melting temperature Tm of polyamide 6 polymer.

Isothermal crystallization kinetics of poly(lactic acid)/synthetic mica nanocomposites

ABSTRACTThe isothermal crystallization kinetics of PLA/fluoromica nanocomposites was studied. Three types of synthetic mica at three concentrations (2.5, 5.0, and 7.5 wt % mica) were used and the effect of these micas on the crystallization and thermal properties of PLA was investigated by differential scanning calorimetry (DSC). The Avrami and Hoffman‐Weeks equations were used to describe the isothermal crystallization kinetics and melting behavior. Addition of these micas to the PLA matrix increased the crystallization rate, and this effect depended on the mica type and concentration. While the nonmodified Somasif ME‐100 exerted the smallest effect, the effect observed for the organically modified Somasif MPE was the most pronounced. The lower half‐time of crystallization t1/2 was around 3 min for the PLA/Somasif MPE nanocomposites containing 7.5 wt % of filler at 90°C, which is about 16 min below that found for neat PLA. The equilibrium melting temperature ( ) of PLA were estimated for these systems, showing an increase in the composites and an increase with increasing loading, except for PLA/Somasif MPE, in which the increase of the mica content decreased about 5°C. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40322.

Ceramic clays from the western part of the Tamnava Tertiary Basin, Serbia: Deposits and clay types

Based on geological, mineralogical, physical, chemical and technological investigations in the Tamnava Tertiary Basin near Sabac town (western Serbia), deposits of ceramic clays were studied. These ceramic clays are composed of kaolin-illite with a variable content of quartz, feldspars, mica, iron oxides and hydroxides, and organic matter. Four main types of commercial clays were identified: i) red-yellow sandy-gravely (brick clays); ii) grey-white poor sandy (ceramic clays); iii) dark-carbonaceous (ceramic clays); and iv) lamellar (?interspersed?) fatty, poor sandy (highly aluminous and ferrous clays). Ceramic clays are defined as medium to high plastic with different ranges of sintering temperatures, which makes them suitable for the production of various kinds of materials in the ceramic industry.

Nanomechanical Characterization Effect of Mica and Aging on Asphalt Binder

AbstractAsphalt concrete (AC) consists of approximately 95% aggregate, by weight. Of this 95%, about 6% is smaller than 0.075 mm in size (passing the #200 sieve and called filler). The fillers often contain mica, which is a formation of silicate minerals having perfect basal cleavage. Mica has been shown to reduce the strength of AC. This study evaluates the effects of mica on asphalt materials subjected to aging. Mica is combined with asphalt binders to make mastics. Mastics are aged at four different levels and tested by nanoindentation to determine modulus and hardness values. It is shown that mastic with no mica becomes much harder after long-term aging. Aged mastic with no mica is shown to be harder than the aged mastics with low concentrations of mica. Mastic with less than 5% mica in the fillers behaves similarly to binder. However, with a mica content of 7.5%, the modulus decreases after long-term aging. A mastic sample containing 5% mica is shown to have the highest modulus value. Therefore, low-...

Studies on the Aging Resistance of Polypropylene Composites Filled with Mica in High Content

PP/mica composites were prepared via melt blending, homemade UV aging box and the constant temperature and humidity aging box were used to study the resistance to aging of the composites, and then the properties were studied by mechanical property test, SEM. Results show that: mica in PP matrix can improve the resistance to UV aging and hygrothermal aging; UVB irradiance within 800h plays a role in improving mechanical properties, the retentions are above 95%; at the beginning of hygrothermal, here are some contributions to tensile strength, the resistance to hygrothermal aging is reducing with the increasing of mica content, when the mica content is 10%, the resistance is best, and the retentions of tensile strength and impact toughness are above 93%.

Pressure–temperature and deformational evolution of high-pressure metapelites from Variscan NE Sardinia, Italy

Chloritoid schists crop out north of the village of Lula in the Inner Zone of the Variscan chain of Sardinia consisting of a variety of metamorphic rocks. The S1 and S2 foliations in these schists are defined by the orientation of muscovite, paragonite, and chloritoid. Chlorite is an additional mineral oriented along S2. Late margarite grew at the expense of chloritoid included in garnet. Garnet porphyroblasts, enclosing quartz, chloritoid, rutile, Fe-oxide, apatite and paragonite, show a progressive decrease of spessartine component from 17 to 7mol% and an increase of pyrope component from 4 to 6mol% from core to rim. The grossular content firstly increases from the inner (Grs~21) to the outer core (Grs~27) and then decreases towards the outermost rim (Grs~15). Compositional mapping of white mica also revealed zoning and a wide range in Si content (from 6.0 to 6.6pfu). The highest Si content is related to the highest Fe and Mg contents and the lowest Na content. P–T pseudosections were calculated in the system Na2O–K2O–CaO–FeO–MnO–MgO–Al2O3–TiO2–SiO2–H2O for compositions of chloritoid schists. The highest Si contents of K-white mica and the garnet core composition suggest pressures close to 1.8GPa and temperatures of 460–500°C. The garnet rim composition and low Si contents in K-white mica are compatible with re-equilibration at 540–570°C and 0.7–1.0GPa. These results suggest an HP-metamorphic imprint during the D1 deformation phase which occurred before the Barrovian amphibolite-facies metamorphism of NE Sardinia. D2 folding and shearing occurred at decreasing P–T conditions during the exhumation of the metamorphic complex.

Effect of Soil Minerals on Potassium Release from Soil Fractions by Different Extractants

Kinetics of potassium (K) release from sand, silt, and clay fractions of 10 calcareous soils of southern Iran were examined to evaluate the ability of different fractions to release K. Samples were successively extracted with 0.01 M CaCl2, HCl, and citric acid for 1496 h. Mineralogical analysis indicated that mica, chlorite, smectite, and palygorskite were the main minerals detected in the clay fraction. The sand and silt fractions were dominated by quartz, feldspars, and micas. Results indicated that the clay fractions released more K than the silt and sand fractions to all extractants (620, 283, and 148 mg kg−1 for clay, silt, and sand fractions, respectively, averaged for 10 samples and three extractants). The ability of acidic extractants to release K from the sand and silt fractions was much higher than that of CaCl2 solution. However, this difference was not significant (p < 0.05) for the clay fraction. For CaCl2, first-order equation, and for acidic solutions, all first-order, Elovich, and parabolic diffusion equations can describe the release rate of K from different soil fractions. Significant relationships (p < 0.05) were obtained between cumulative K released to three extractants and b and a values of Elovich equation with mica content in the clay fractions. Generally, the data presented here demonstrate the importance of clay fractions in K supply to plants in calcareous soils of southern Iran.

Effect of Mica Content on the Physical, Mechanical and Morphological Properties of Alumina-Cullet-Mica Ceramic

This research is conducted in order to determine the best composition of alumina-cullet ceramic with the addition of mica powder. The alumina-cullet-mica composites (ACMCs) were produced by using powder compaction method. All raw materials used such as alumina, cullet and mica for fabricating the samples were first mixed, compacted and finally the samples have to undergo the sintering process. It is observed from the physical, mechanical and morphological analyses that the properties of ACMCs are highly dependable on the mica content.

Epoxy/MICA 복합체의 MICA 충진함량 변화에 대한 기계적, 전기적 특성연구

This paper reported a study on the thermal, mechanical and electrical insulation properties of epoxy/mica composites. To investigate the effect of mica content, glass transition temperature, mechanical properties such as tensile and flexural strength, and insulation breakdown properties for epoxy composites with various contents of mica. The effect of insulation thickness on insulation breakdown property was also studied. It was observed that tensile and flexural strength decreased with increasing mica content, while elastic modulus increased as the mica content increased. AC insulation breakdown strength for all epoxy/mica composites was higher than that of neat epoxy and that of the system with 20 wt% mica was 14.4% improved. As was expected, insulation breakdown strength at 30℃ was far higher than that at 130℃, and it was also found that insulation breakdown strength was inversely proportion to insulation thickness.

Rheological behavior of poly(lactic acid)/synthetic mica nanocomposites

Poly(lactic acid) nanocomposites were prepared with three synthetic fluoromicas in a twin-screw extruder. Sodium and two organomodified synthetic fluoromicas at different compositions were used. The effect of mica type and composition on the rheological behavior of the nanocomposites was evaluated. The sodium fluoromica did not have a significant effect on the poly(lactic acid) rheological properties, while addition of the organophilic micas to poly(lactic acid) has a strong effect on the rheology, showing a pronounced shear thinning behavior. The dynamic rheological studies revealed that the nanocomposites with organomica have a higher viscosity and more pronounced elastic properties than neat poly(lactic acid). Both storage and loss moduli increased with mica content.

The mineral chemistry, near-infrared, and mid-infrared reflectance spectroscopy of phengite from the Olympic Dam IOCG deposit, South Australia

Phengite is the main potassic dioctahedral mica identified at the Olympic Dam iron oxide–copper–gold (IOCG) deposit, South Australia, where its mineral chemistry is quite variable. These differences can be explained by contrasting degrees of hydrothermal alteration. In the heavily-sericitized, ore-bearing rocks, the phengites display a lower-Si content, a higher-Al content, and a lower Mg-number than the phengites from the weakly-sericitized alteration halo that surrounds the deposit. Variations are also observed in the near- and mid-infrared reflectance spectra collected from phengite-bearing rocks. In the near-infrared, high-Al phengite produces a spectral absorption feature at 2.206μm, and this feature is displaced to 2.213μm for low-Al phengite. In the mid-infrared, high-Al phengite produces a strong reflectance peak at 9.59μm, whereas this peak is observed at 9.57μm in the spectra from low-Al phengite. Additional peaks were also identified at 10.98, 12.22, and 13.33μm. These were most intense in the spectra from high-Al phengite. A drill core profile was produced using the results of the spectral analysis that shows the change in phengite mineral chemistry and phengite abundance as a function of depth. In general, near- and mid-infrared reflectance spectroscopy can be used to characterize the aluminum content of potassic dioctahedral micas like phengite, and this information can be used to infer the degree of sericitic alteration that has occurred as a result of hydrothermal fluid flow.