Anorthite Feldspar Research Articles

Mineralogical properties of the Quaternary deposits in the Iraqi highway, east of Al Warka city- Southern Iraq

The study was carried out on sub-surface sediments of quaternary deposits in the southern part of the Iraqi highway-east of the Al Warka city, Southern Iraq. This study has been focused on the variety of sedimentary environments in the quaternary period. The variations in mineralogy and texture with depths gave an indicator of environmental change. Silt, sandy silt, silt loam and sandy loam are most of sediments texture variation with depths. Quartz, anorthite feldspar, dolomite, calcite, Mg-Ca calcite, and gypsum are most of the light minerals in the studied area. Quartz and feldspar are dominant form depth intervals between 1 to 5 meters. Calcite is predominant at depth 6 meters with high shell fragments reached 38% as an indicator to change of sedimentary environments from depth interval 6 to 12m. The rate of shells growth at 6m depth was much higher in the fine-sediment and nutrient-rich channel, this conclusion may be an indicator of environmental change at this depth, suggests a high nutrient content in the river at this period allowed for molluscs shell growth. Opaque minerals, Chlorite, Pyroxene, biotite, epidote, staurolite, zircon, tourmaline, and rutile are most of the heavy metals. Chlorite, biotite, pyroxene, zircon, garnet, and rutile are increase with depths, while opaque and celestite are decreasing with depths. Chlorite, illite, and kaolinite are most of the clay minerals. Illite and kaolinite are increase with depths, while chlorite is decreased with depths.

Chemical Analysis of Silica Fume Infused Self Healing Concrete

Self healing technique using mineral and chemical admixtures are gaining momentum nowadays. Admixtures like silica fume, marble dust, fly ash, ground granulated blast furnace slag, limestone powder are being experimented nowadays as self healing agents. In this experimental examination, silica fume has been used as a healing agent (12.5% replacement). Cracks were induced and the specimens were subjected to continuous water exposure for 28 days. After 28 days, the specimens were tested for healing effect and the healing products were chemically analyzed by means of FESEM analysis, EDAX, thin section test and XRD analysis. From FESEM and EDAX analysis, for silica fume mix, portlandite formation was evident. Thin section analysis showed the morphology of anorthite feldspar. XRD analysis showed that excess silica content in silica fume actively involved in faster healing process resulting in the formation of calcite, calcium hydroxide and calcium carbonate. All the test results indicated that self healing property can be achieved using silica fume as mineral admixture. In addition to the healing property, incorporating silica fume reduces the consumption of cement, thereby reducing the air pollution caused by the cement industries as well as resulting in the production of eco-friendly concrete.

Mineral Properties of Euphrates and Shatt Al-Arab River Sediments

The mineralogical research described in this paper was carried out during 2018, about 30 samples from twelve river core sediments (from S1 to S12)at six sites in Euphrates and Shatt Al-Arab rivers from Hilla to Basrah cities. The coordinate number of these cores are between 38°41°32.48''N-38°14'24.10”N latitude and 39°56’4.59”E-39°8°13.41”E longitude. The mineralogy is determined by X-ray diffraction, and reveals that carbonate minerals, quartz, and anorthite feldspar are the main of light minerals in the different depth intervals, while Kaolinite, palygoreskite and chlorite are the main of clay minerals. Calcite and dolomite are more abundance than quartz. Calcite is present at high percentage in Basrah city (S11) compare with the other area.The highest value of dolomite is pointed in Diwaniya (S4) and Qurna (S9), whereas the lowest in Simawa and Nasiria cities (S5 and S8). The abundant ratio of quartz reduces to south Euphrates River direction and downward of depth intervals. Anorthite feldspar is absent in Nasiria and Basra, whereas it is present in other sites. Major oxides represented by SiO2, AhO3, Fe2O3, CaO, MgO, Na2O, K2O, and TiO2are the main in the sediments, it detect by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) analyses. Silica is attribute to quartz minerals, while alumina is connect with clay minerals. The domination of calcite with lack of dolomite reflected in the low content of the MgO. Redox elements (Fe and Ti) contents in the sediments of studied cores were high within the uppermost part of the profiles, but with increase the depth it have undergoing some degree of depletion. Sodium is originated from halite, and clay minerals, while potassium from illite. Micro and nano texture features took place by SEM-EDAX. There are several of mechanical and chemical features are detected; conchoidal, rounded, pits, and microgranular. These features resulted from dissolution by river water (chemical) or during long distance of transportation.

Terminal particle from Stardust track 130: Probable Al-rich chondrule fragment from comet Wild 2

A 4×6μm terminal particle from Stardust track 130, named Bidi, is composed of a refractory assemblage of Fo97 olivine, Al- and Ti-bearing clinopyroxene and anorthite feldspar (An97). Mineralogically, Bidi resembles a number of components found in primitive chondritic meteorites including Al-rich chondrules, plagioclase-bearing type I ferromagnesian chondrules and amoeboid olivine aggregates (AOAs). Measured widths of augite/pigeonite lamellae in the clinopyroxene indicate fast cooling rates suggesting that Bidi is more likely to be a chondrule fragment than an AOA. Bulk element concentrations, including an Al2O3 content of 10.2wt%, further suggests that Bidi is more akin to Al-rich rather than ferromagnesian chondrules. This is supported by high anorthite content of the plagioclase feldspar, overall bulk composition and petrogenetic analysis using a cosmochemical Al2O3–Ca2SiO4–Mg2SiO4 phase diagram. Measured minor element abundances of individual minerals in Bidi generally support an Al-rich chondrule origin but are not definitive between any of the object types. Oxygen isotope ratios obtained from olivine (+minor high-Ca pyroxene)fall between the TF and CCAM lines and overlap similar minerals from chondrules in primitive chondrites but are generally distinct from pristine AOA minerals. Oxygen isotope ratios are similar to some minerals from both Al-rich and type I ferromagnesian chondrules in unequilibrated carbonaceous, enstatite and ordinary chondrites. Although no single piece of evidence uniquely identifies Bidi as a particular object type, the preponderance of data, including mineral assemblage, bulk composition, mineral chemistry, inferred cooling rates and oxygen isotope ratios, suggest that Bidi is more closely matched to Al-rich chondrules than AOAs or plagioclase-bearing type I ferromagnesian chondrules and likely originated in a chondrule-forming region in the inner solar system.

The influence of Fe-rich coatings on the dissolution of anorthite at pH 2.6

Surface coatings are very common on mineral grains in soils but most laboratory dissolution experiments are carried out on pristine, uncoated mineral grains. An experiment designed to unambiguously isolate the effect of surface coatings on mineral dissolution from any influence of solution saturation state is reported. Two aliquots of 53 to 63 μm anorthite feldspar powder were used. One was dissolved in pH 2.6 HCl, the other in pH 2.6 FeCl 3 solution, both for ∼6000 h in flow-through reactors. An amorphous Fe-rich, Al-, Ca- and Si-free orange precipitate coated the anorthite dissolved in the FeCl 3 solution. BET surface area of the anorthite increased from 0.16 to 1.65 m 2 g −1 in the HCl experiment and to 3.89 m 2 g −1 in the FeCl 3 experiment. The increase in surface area in the HCl experiment was due to the formation of etch pits on the anorthite grain surface whilst the additional increase in the FeCl 3 experiment was due to the micro- and meso-porous nature of the orange precipitate. This precipitate did not inhibit or slow the dissolution of the anorthite. Steady state dissolution rates for the anorthite dissolved in the HCl and FeCl 3 were ∼2.5 and 3.2 × 10 −10 mol feldspar m −2 s −1 respectively. These rates are not significantly different after the cumulative uncertainty of 17% in their value due to uncertainty in the inputs parameters used in their calculation is taken into account. Results from this experiment support previous theoretical and inference-based conclusions that porous coatings should not inhibit mineral dissolution.

Nucleation and Crystallization of New Glasses from Fly Ash Originating from Thermal Power Plants

The nucleation and crystallization kinetics of new glasses obtained by melting mixtures of a Spanish carbon fly ash with glass cullet and dolomite slag at 1500°C has been evaluated by a calculation method. These glasses, whose microstructure was examined by TEM carbon replica, were susceptible to controlled crystallization in the 800°–1100°C range. The resulting glass‐ceramics developed acicular and branched wollastonite crystals or a network of dendritic pyroxene mixed with anorthite feldspar (SEM and EDX analysis). The time–temperature–transformation curves (processing of the XRD data) showed the crystallization kinetics and the critical cooling rate to be in the 12°–42°C/min range.

Isosymmetric structural phase transitions: phenomenology and examples

Structural phase transitions ('type 0') in which there is no change of space group or of the occupied Wyckoff sites contrast with others in which diffusionless transformation can occur in a single step between higher-and lower-symmetry space groups (type I), through a low-symmetry transition state between relatively higher-symmetry initial and final structures (type II), and those where the mechanism is necessarily more complex (type III). A phenomenological model shows that type 0 transitions are necessarily first order, and may terminate at a critical point. The corresponding supercritical behaviour is a 'crossover' or 'diffuse transition' in which there is no discontinuity in any free-energy derivative. However, the location of the crossover is precisely defined at a minimum in the second derivative of the free energy with respect to a suitable order parameter. Isosymmetric transitions and/or crossovers occur in important mineralogical systems (pyroxenes, feldspars and carbonates) and non-linear optic materials (KTiOPO 4 ). Non-monotonic variation of free-energy derivatives around the crossover can have a serious effect on the locations and slopes of phase equilibria in pressure-temperature space. Interaction between non-symmetry-breaking and symmetry-breaking order parameters appears to play a major role in stabilizing low-symmetry clinopyroxene and anorthite feldspar phases.