Abstract Gold mineralization in the El-Barramiya region of Eastern Desert, Egypt, is connected to post-accretionary stage throughout Central Desert. It represented by quartz, quartz-carbonate veins and disseminations listvenite rocks. The thrust contact between rock units area played an imperative part gold where obduction ophiolitic rocks over metasediments metavolcanics caused shear zones. Mi...

Gold production in New Zealand has been significant since the mid 1800s, totalling 900 t (29 Moz) to 2005. In addition, there is potential for a further 1230 t (39.5 Moz) of gold in known and undiscovered deposits. Most of the gold has originated from epithermal and mesothermal (orogenic) hydrothermal systems. Epithermal gold occurs in the Northland, Coromandel and Taupo volcanic zones in quart...

– X-ray diffraction (XRD) experiments have been carried out on quartz-like α−GaPO4 at high pressure and room temperature. A transition to a high pressure disordered crystalline form occurs at 13.5 GPa. Slight heating using a YAG infrared laser was applied at 17 GPa in order to crystallize the phase in its stability field. The structure of this phase is orthorhombic with space group Cmcm. The ce...

The value of surface complexation modeling of radionuclide adsorption in supporting the selection of KI values should be given wider recognition within the performance assessment modeling process. Studies of uranium(Vl) adsorption by a weathered schist and specimen mineral phases that comprise the schist were conducted as a function of aqueous chemical conditions in laboratory experiments. The ...

First-principles molecular dynamics simulations at constant pressure have been used to investigate the mechanisms of compression of liquid SiO2. Liquid SiO2 is found to become denser than quartz at a pressure of about 6 GPa, in agreement with extrapolations of lower pressure experimental data. The high compressibility of the liquid is traced to medium-range changes in the topology of the atomic...

Theoretical calculations are performed to study transformations in silica as a function of nonhydrostatic stress. Molecular-dynamics calculations reveal a crystalline-to-crystalline transition from a-quartz to a phase with five-coordinated silicon (Si) at high pressure in the presence of deviatoric stress. The phase, which appears for specific orientations of the stress tensor relative to the c...

Metamorphic index mineral zones, pressure– temperature (P–T) conditions, and CO2–H2O fluid compositions were determined for metacarbonate layers within the Wepawaug Schist, Connecticut, USA. Peak metamorphic conditions were attained in the Acadian orogeny and increase from 420 C and 6.5 kb in the low-grade greenschist facies to 610 C and 9.5 kb in the amphibolite facies. The index minerals olig...

Lithium concentrations and isotopic compositions in the country rocks (amphibolites and schists) of the Tin Mountain pegmatite show systematic changes with distance to the contact. Both Li and δLi decrease dramatically along a ∼10m traverse from the pegmatite into amphibolite, with Li concentration decreasing from 471 to 68ppm and δLi decreasing from +7.6 to −19.9. Rubidium and Cs also decrease...