C–O isotope geochemistry of the Florida phosphate of Four Corners and Hardee County mines, USA: Implication for genesis and diagenesis

© 2017 Elsevier B.V. The study area located in Florida, USA and emphasized on low-grade phosphorites in Hardee County (HC) and Four Corners (FC) mining areas. The main purpose of this study is to apply a standard geochemical technique to understand the diagenetic history and paleo-environmental aspects of phosphates within one of the major phosphate deposits in the USA. The effect of diagenesis on the phosphate minerals was studied by isotope analysis of the phosphate bone fragments and phosphatized mudclasts and rods. The environmental conditions that prevailed during the life of organisms were assessed by isotope analysis of the shark teeth. In this paper, variation in stable isotope (δ18O and δ13C) signatures of structural carbonate in rocks and shark teeth were studied in Florida phosphate. The studied samples show negative values for both δ13C and δ18O isotopes of structural carbonate. The light mudclast samples shows higher oxygen ratios (− 1.6) than the dark mudclasts (− 2.3) in Hardee County, whereas those values were lower, − 2.3 and − 3, respectively, in Four Corners samples. The shark teeth found in the deposits show narrow variations in values of δ13C (− 3.4 to − 4.9%o) and δ18O (− 1.4 to 2.1%o) isotope. The bone fragments in the deposits are more similar to the light mudclasts regarding the isotope ratios and carbonate content. The alteration is evident in the Florida phosphorites where δ18O values of bulk teeth are higher than those of bones and mudclast. This alteration could be because of increasing crystallinity and decreasing carbonate content with increasing depth of burial

A qualitative study of airborne minerals and associated organic compounds in southeast of Cairo, Egypt

© 2018 by the authors. Licensee MDPI, Basel, Switzerland. This study is concerned with the identification of the mineralogical composition of dust fall samples collected from southeast of Cairo, Egypt. The mineralogical identification was conducted by means of the polarizing microscope, infra-red spectroscopy (IR), and X-ray diffraction (XRD). The relationship between the mineralogical composition of dust fall samples and 10 rock samples from the surrounding terrains were investigated. The major mineralogical species existing in the atmosphere of the study area are: carbonates mainly in the form of calcite in addition to the appearance of the dolomite form in traces overall the study area, but with considerable observation in the southern region; quartz which is less than calcite in its abundance; sulphates in the form of gypsum which may also be present as traces in the anhydrite form. Trace constitution of feldspars; clay minerals in the form of kaolinite, illite, and montimorillonite; and halite are also observable in the same samples. Organic compounds are present in the atmosphere of the area mainly as alkanes with presence of traces of phosphines. This study qualitatively shows the mineralogy of air particulate over rock processing area and the obtained results indicates that the main pollution source in the study area is the industrial activities with minor contribution of the natural sources, especially erosion and dust carried by winds from the surrounding terrains Cairo in the southern direction. This study provides useful results for the contribution of rock processing activities to the mineral composition of atmospheric particulates

On the mineral characteristics and geochemistry of the Florida phosphate of Four Corners and Hardee County mines

© 2016 Elsevier B.V. The Florida phosphate deposits in Four Corners and Hardee County mines are composed mainly of phosphate minerals and quartz in addition to subordinate proportions of feldspars, dolomite, calcite, gypsum, kaolinite, attapulgite and montmorillonite. These phosphorites contain three structurally different types of mudclasts: massive mudclasts, mudclasts with concentric structure and mudclasts consisting of agglomerates of apatite microparticles. The latter are represented by particles resembling phosphatized fossil bacteria associated with microbial filaments, and hollow apatite particles having surfacial coatings and connected to microbial filaments. The Florida phosphate particles are reworked and vary in mineral composition, color and shape. They are composed of a mixture of well-crystalline species including carbonate fluorapatite (francolite), carbonate apatite and fluorapatite. The color variation of the phosphate particles is related to difference in mineral composition, extent of diagenetic effects and reworking. The light-colored mudclasts are characterized by the presence of carbonate apatite and aluminum hydroxide phosphate minerals, whereas the dark mudclasts are rich in iron aluminum hydroxide phosphate minerals. The Florida phosphorites are suggested to be formed partially by authigenetic precipitation, replacement of the sea floor carbonate and diatomite, and microbial processes. With respect to elemental geochemistry, the analyzed particles contain small percentages of sulfur and iron which are related to the occurrence of pyrite. Traces of silica and alumina are recorded which may be attributed to the diagenetic. Some of the tested particles are relatively rich in phosphorous, fluorine, calcium, and magnesium, while poor in silicon, potassium and sulfur. Whereas, the bioclasts (especially teeth) are relatively rich in calcium, phosphorous and fluorine while poor in silicon, aluminum, magnesium and potassium. Hence, the microchemical analyses revealed that differential diagenesis affected mudclasts more than bioclasts. There is a complete compositional gradation between clay and phosphate particles which reflects their interaction. This involved kaolinitization of the phosphate particles, phosphatization of the clay mineral particles and production of silica

A Qualitative Study of Airborne Minerals and Associated Organic Compounds in Southeast of Cairo, Egypt

This study is concerned with the identification of the mineralogical composition of dust fall samples collected from southeast of Cairo, Egypt. The mineralogical identification was conducted by means of the polarizing microscope, infra-red spectroscopy (IR), and X-ray diffraction (XRD). The relationship between the mineralogical composition of dust fall samples and 10 rock samples from the surrounding terrains were investigated. The major mineralogical species existing in the atmosphere of the study area are: carbonates mainly in the form of calcite in addition to the appearance of the dolomite form in traces overall the study area, but with considerable observation in the southern region; quartz which is less than calcite in its abundance; sulphates in the form of gypsum which may also be present as traces in the anhydrite form. Trace constitution of feldspars; clay minerals in the form of kaolinite, illite, and montimorillonite; and halite are also observable in the same samples. Organic compounds are present in the atmosphere of the area mainly as alkanes with presence of traces of phosphines. This study qualitatively shows the mineralogy of air particulate over rock processing area and the obtained results indicates that the main pollution source in the study area is the industrial activities with minor contribution of the natural sources, especially erosion and dust carried by winds from the surrounding terrains Cairo in the southern direction. This study provides useful results for the contribution of rock processing activities to the mineral composition of atmospheric particulates