Silicate minerals

About: Silicate minerals is a research topic. Over the lifetime, 1794 publications have been published within this topic receiving 67064 citations.

Processes Controlling Groundwater Chemistry from Mulakalacheruvu Area, Chittoor District, Andhra Pradesh, South India: A Statistical Approach Based on Hydrochemistry

Abstract: In India groundwater is an important source for domestic and agricultural purposes. Management of this resource is very important to meet the increasing demand of water. In this study, the ionic concentrations of groundwater from Mulakalacheruvu area, Chittoor district, Andhra Pradesh, South India have been calculated during May 2014 and the major ionic concentrations have been analyzed by hydrochemcial and statistical methods in order to trace the main processes controlling the groundwater chemistry. The results have suggested that these groundwater samples belong to Na-HCO3 (18 samples), Ca-HCO3 (16 samples) and Mg-HCO3 (6 samples) types. The hydrochemical methods suggest that the rocks in the aquifer system are sources of the major ions in the groundwater, and the silicate is the main mineral phase. Three sources viz. mafic silicate, felsic silicates and easily soluble minerals have been identified as responsible for the chemical variations of the groundwater. Further, the source contributions of silicate minerals for the groundwater hydrochemistry have been analyzed. These results suggest that the hydrochemistry of the groundwater in the south-eastern area is mainly controlled by weathering of felsic silicate (61-100%), whereas the north-western area is principally contributed by mafic silicate minerals (48-100%).

Mineralogical and Geochemical Transformation of Clays During Catagenesis and Their Relation to Oil Generation

Abstract: Catagenesis of the Upon burial of the sediments, the concentration of expandable 2:1 layer silicates, kaolinite and amorphous inorganic material decreases while illite increases in concentration in the 2.0 μm fraction. The same trend is observed in the 4+ by Al3+ and the ensuing absorption of K+ and occurs prior to the onset of hydrocarbon generation from the sedimentary organic matter. Water is not only released to the pore system by clay dehydration but also by dissolution of amorphous inorganic matter and destruction of layer silicate minerals. Only the last of these mechanisms is operative within the zone of oil generation.

The Iron and Titanium Minerals in the Titaniferous Ferruginous Latosols of Hawaii

Abstract: Titaniferous Ferruginous latosols are an important group of Hawaiian soils. They have developed by pedogenetic weathering of the volcanic materials of basic and ultrabasic lava flows and their associated pyroclastic materials, under climatic conditions having definite alternating dry and wet seasons. The annual rainfall range for these soils is 30 to 60 inches. Under the native and undisturbed vegetation, these soils have a profile of very friable silt material with very little horizon differentiation. When exposed to dehydration by removal of the protective canopy cover of the forest, as occurs after forest fires, a tremendous change occurs in the soil profile morphology. The change is greater than the morphological differences which normally occur between the profiles of the Great Soil groups. A surface indurated horizon develops in which the bulk density and particle density have an approximate two-fold increase. The mineralogical changes are substantial. The amorphous hydrated titanium and iron oxides are converted into good crystalline forms of anatase, rutile, pseudo-brookite, titanohematite and titanomaghemite. In some cases these minerals develop from the weathering of titanomagnetite-ilmenite mixed crystals. The unusual characteristic of these soils is the apparent movement of the colloidal material in a very short space of time, which results in an accumulation of titaniferous minerals in the indurated surface horizon and the accumulation of amorphous silica giving weak X-ray diffraction patterns of alpha quartz on the very surface of the soil. Rutile is also identified along with the silica at the surface. Aluminum oxides are removed to the lower horizons and in some cases accumulated as irregularly shaped gibbsite nodules in scattered pockets below the clay horizon. TITANIFEROUS FERRUGINOUS LATOSOLS include soils which have horizons rich in titanium and iron oxides. This group of soils has formed from the basic and ultrabasic lavas and pyroclastic materials of the post-erosional volcanic activity which has occurred on the geologically old islands of the Hawaiian group. There is strong evidence that the formation of these soils may be limited to the pyroclastic materials of post-erosional origin. The pedogenetic weathering of the original primary minerals evidently has been intense, as all of the silicate minerals have been completely decomposed. Leaching has been thorough and unimpeded, as the bases have 1 Published with the approval of the Director of the Hawaii Agricultural Experiment Station, Honolulu, as Technical Paper No. 559. Manuscript received February 20, 1969. 2 Hawaii Agricultural Experiment Station, University of Hawaii, Honolulu, Hawaii 96822. 3 Tokyo Institute of Technology, Tokyo, Japan. been removed to an extremely low level. These soils have attracted much attention because of the marked changes which occur in their chemical, physical, and mineralogical composition when they have become exposed and are dehydrated by the removal of their forest canopy and tall grass cover by fire, over-grazing, or other activities of man. The profile morphology of the soil changes from a friable silt profile having little horizonal differentiation and similar to Reddish Prairie profile to one having an indurated high bulk density surface horizon and a morphology similar to that described for the laterite profile formed ill situ. These soils have been studied and described by several workersFujimoto et al. (1948), Katsura et al. (1962), Sherman et al. (1948), Sherman et al. (1953), and Tamura et al. (1955). The purpose of this paper is to identify some of the mineralogical changes which result from

Stability of Epidote Minerals

Abstract: A NUMBER of silicate minerals have proved difficult to synthesize by the commonly employed methods involving hydrothermal crystallization of glasses or reactive oxide mixes of suitable composition. Failure to synthesize a phase may be caused by the experimental conditions not being within the region where the phase is thermodynamically stable. But, in some cases, failure simply reflects a large nucleation barrier to the formation of the stable phase so that metastable phases which nucleate with ease form, and may persist indefinitely. Several workers1–3 have considered this problem in relation to the epidote minerals, and the consistent failure of low-pressure synthesis could indicate that these phases may be stable only under relatively high-pressure conditions. Geological occurrence does not entirely support this proposition. The results presented here indicate that with these minerals nucleation is a sluggish process at low pressures, and if this step is by-passed, growth is readily achieved from the phases which normally form in synthesis. This sluggish nucleation is possibly related to the structure of the minerals.