نتایج جستجو برای: carbonate mineral
تعداد نتایج: 89983 فیلتر نتایج به سال:
Microbial carbonate mineralization is widespread in nature and among microorganisms, and of vast ecological and geological importance. However, our understanding of the mechanisms that trigger and control processes such as calcification, i.e., mineralization of CO2 to calcium carbonate (CaCO3), is limited and literature on cyanobacterial calcification is oftentimes bewildering and occasionally ...
Crustaceans, like most mineralized invertebrates, adopted calcium carbonate mineralization for bulk skeleton reinforcement. Here, we show that a major part of the crustacean class Malacostraca (which includes lobsters, crayfishes, prawns and shrimps) shifted toward the formation of calcium phosphate as the main mineral at specified locations of the mandibular teeth. In these structures, calcium...
The Zaraj-Sou bauxite deposit (southwest of Ramsar, Mazandaran Province, northern Iran) was developed as discontinuous stratified layers and/or lenses along the boundary between carbonate rocks of the Elika (Triassic) and shales and sandstones of the Shemshak (Lower Jurassic) formations. Diaspore, kaolinite, hematite, and anatase are the major mineral phases of the ores. Texturally, the bauxite...
Rock unites which are exposed in Tak-I mine area are: Taknar formation (Ordovician), Mid-late Paleozoic and younger intrusive rocks. Taknar formation consists of sericite schist, chlorite schist, chlorite-sericite schist and some meta-diabase- gabbro-diorite. Taknar Polymetal (Cu-Zn-Au-Ag-Pb) Massive sulfide deposit formed at certain horizon of Taknar formation. Three style of mineralization ar...
The transition from invertebrate calcium carbonate-based calcite and aragonite exo- and endoskeletons to the calcium phosphate-based vertebrate backbones and jaws composed of microscopic hydroxyapatite crystals is one of the great revolutions in the evolution of terrestrial organisms. To identify potential factors that might have played a role in such a transition, three key domains of the vert...
Simple folded Zagros has several phosphate horizons with the Cretaceous – Tertiary ages that are present as inter-layer in Pabdeh and Gurpy formations. Therefore, study of combination, texture of mineralogy and determination of genesis of marine phosphate of Zagros basin during Eocene – Oligocene is important. In this study, 28 samples were collected from phosphate Kuhe-e- Sefid and Kuh-e- Lar ...
One of the metamorphic rocks in the Nain ophiolitic mclange is skarn which is fonned during the contact metamorphism of intrusive tonalites with their neighboring limestones and carbonate parts of banded cherts. Minerals of these skarns consist of carbonate (calcite). clinopyroxene (diopside). garnet (grossular-andradite). wollastonite, sphene and epidote. Also tonalites contain quartz, pl...
Hormuz series in Zendan salt dome, Neoprotozoic-Early Cambrian rocks is located near Bandar-e-Lengeh in western Hormozgan Province. In this salt dome, iron calcic skarns are present near the basic igneous bodies that have copper hydrothermal deposits. Carbonate sedimentary sequences, carbonate tuffs and igneous rocks are the host rocks of these skarns. The calcsilicates in the endoskarn include...
The process of mineral formation following periods of growth interruption (growth bands) is described. Flat pearl implantation as well as a new trepanning method are used to observe the transitory phases of calcium carbonate which nucleate and grow during this process. An initial random nucleation of the aragonite polymorph is observed followed by a transition towards spherulitic growth. During...
Infrared spectroscopy (IR) is a powerful tool to decipher the molecular groups in the minerals. This technique of detection, using atomic vibrations of molecules, that is identified through a process of absorption, makes possible the necessary mechanisms of phase analysis of minerals. In this paper, after a brief description of infrared spectroscopy, two groups of minerals will be explained by ...
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