high pressure, low temperature metamorphic rock formed in a subduction zone, mined out locally and used as jetty rock for the Coquille River Jetty at Bandon, OR. May contain glaucophane, actinolite, garnet, quartz, muscovite, pyrite, and probably sodium plagioclase.

FeS2 is Pyrite structured and crystallizes in the cubic Pa-3 space group. The structure is three-dimensional. Fe3+ is bonded to six equivalent S+1.50- atoms to form corner-sharing FeS6 octahedra. The corner-sharing octahedral tilt angles are 64°. All Fe–S bond lengths are 2.25 Å. S+1.50- is bonded in a 3-coordinate geometry to three equivalent Fe3+ atoms.

pressure oxidation process, gold bearing pyrite is subjected to high-temperature, high-pressure oxidation in autoclaves to destroy pyrite lattice.12,13 This process has been practiced commercially since the early1980s,14 and is widely accepted by the gold mining industry all over the world for its high efficiency and low pollution.

The new high-pressure IrO2 phase has a pyrite-type structure with space group Pa-3 and cubic symmetry. The phase was stable at pressures up to 50 GPa. The pyrite-type IrO2 structure is …

Three pressure‐induced polyamorphs in GeO 2 glass are recognized unambiguously at high pressure, i.e., α‐quartz‐like, rutile‐like, and pyrite‐like amorphous structures. The obtained knowledge of these polyamorphs is helpful for understanding the mechanisms of network compression behavior and physical properties of SiO 2 and GeO 2 ...

Through high-pressure-temperature experiments in a laser-heated diamond anvil cell at 107–136 GPa and 2,400 K, we discovered an ultradense hydrous phase in (Fe0.8Al0.2)OOH with a previously unknown hexagonal lattice. The team includes Li Zhang, Hongsheng Yuan, Ho-kwang Mao of HPSTAR, and Yue Meng of High Pressure Collaborative Access Team ...

The pyrite-type high-pressure form of FeOOH is predicted from first principles, and found experimentally to be stable under the conditions at the base of the mantle, with implications for ...

Abstract Being as the most abundant natural mineral among the iron-based sulphides, iron pyrite (FeS2) has been extensively investigated. These investigations mainly focused on the known marcasite (Pnnm) and pyrite ( P a 3 ¯ ) phases, due to unknown of high pressure (HP) structural phases of FeS2. Here, we report a theoretical study up to 300 GPa to uncover a brand new monoclinic HP phase of ...

The pressure dependence of electrical resistivity of FeS 2 (pyrite) has been studied with the help of a simple analytical relation. The calculated results are found in reasonable agreement with the experimental measurements. The computed results are then utilized for the evaluation of pressure dependence of band-gap of FeS 2 (pyrite). The ...

Recently, a great deal of attention has been paid to the high-pressure polymorphs of FeOOH (space groups P2 1 nm and Pnnm). These structures potentially form a hydrogen-bearing solid solution with AlOOH and phase H (MgSiO 4 H 2) that may transport water (OH –) deep into the Earth's lower mantle. Additionally, the pyrite-type polymorph (space ...

the light element budget of the core, consistent with high pressure partitioning experiments on Fe–S–silicate systems (Li and Agee 2001; Li et al. 2001) which show that sulfur's affinity for iron increases with pressure . Pyrite, the cubic (Pa3) form of FeS 2, is …

Equation of state, elasticity, and shear strength of pyrite under high pressure. Download. Related Papers. Deformation of polycrystalline MgO at pressures of the lower mantle. By Sebastien Merkel. Deformation of (Mg0.9,Fe0.1)SiO3 Perovskite aggregates up to 32 GPa. By Sebastien Merkel.

The pressure effect on crystal structures, lattice vibrations, and electrical transport properties of Pd S 2 and NiS e 2 were studied under high pressures of up to ∼50 GPa using Raman spectroscopy and electrical resistivity measurements. Pd S 2 undergoes semiconductor-to-metal transition at a pressure of ∼7 GPa without a structural phase transition. . Structural transition to the pyrite ...

If pressure is applied, the coordination number of palladium atoms increases and the three-dimensional pyrite-type structure with octahedral (PdSe₆)⁴⁻ coordination geometry is observed. For the first time, single crystals of a pyrite-type PdSe₂ modification could be obtained and characterized, which were grown by multianvil high ...

The effect of pressure on Fe–S phase equilibria. High-pressure phase relations in the Fe–S system have been explored to high T and P, and the pyrite–pyrrhotite relation persists to P and T conditions well beyond those found along the Earth`s subduction geotherms.

The pressure-dependent elastic properties of the Fe–S system are important to understand the dynamic properties of the Earth's interior. We have therefore undertaken a first-principles study of the structural and elastic properties of FeS2 polymorphs under high pressure using a method based on plane-wave pseudopotential density function theory. The lattice constants, elastic constants ...

The pyrite-type high-pressure form of FeOOH Hydrogen (H) is the most abundant element in the universe and it has played an important role in the structure, dynamics, and evolution of the Earth. About 70% of the Earth's surface is covered with water (H 2O) and a huge amount of water is also estimated to be maintained in the Earth's interior.

High-pressure synthesis of denser glass has been a longstanding interest in condensed-matter physics and materials science because of its potentially broad industrial application. Nevertheless, understanding its nature under extreme pressures has yet to be clarified due to experimental and theoretical challenges. Here we reveal the formation of $mat{OS}{mat{i}}_{4}$ tetraclusters ...

A systematic examination of structural phase transitions and mechanical properties for TiO 2 under high pressure has been performed by using first‐principles calculations. First, we show that the orthorhombic Pca21 structure becomes stabilize at certain pressure and temperature, whereas the cubic fluorite and pyrite structures are not energetically viable in the whole pressure range of 0 ...

As the carbonate buffer system was weaker in the high pressure experiments due to the tenfold dilution of the inflowing water, the effect of pyrite oxidation resulted in a minor influence on the pH (values of 6.2–7.5), even as the pyrite oxidation rates were smaller in the high pressure experiment compared to the low pressure experiments.

system for the production of high-pressure steam. Pyrite grain size is usually s up to 6mm in diameter. The coarser the grain, the higher the gas velocity must be to maintain the bed in a fluidized state. Even flotation pyrites with a grain size less than 70 µm can be processed in the fluid bed roaster. Gas velocity

The pyrite-type high-pressure form of FeOOH Nature. 2017 Jul 13;547(7662):205-208. doi: 10.1038/nature22823. Epub 2017 Jul 3. Authors Masayuki Nishi 1 2, Yasuhiro Kuwayama 1 3, Jun Tsuchiya 1 2, Taku Tsuchiya 1 2 Affiliations 1 Geodynamics Research Center, Ehime University, 2-5 Bunkyo-cho, Matsuyama, Ehime 790 ...

Silica (SiO2) exhibits extensive polymorphism at elevated pressures. X-ray diffraction measurements showed that a high-pressure form with a pyrite-type structure, denser than other known silica phases, is stable above 268 giga-pascals and 1800 kelvin. The silicon coordination number increases from 6 …

At pressures higher than 90 GPa, we also observed the occurrence of a new high-pressure phase of pyrite-type (modified-fluorite type) structure (Pa3̄) that is denser than other known GeO 2 phases. Our results were consistent with the high-pressure transition sequence of tin dioxide (SnO 2 ) …

Previous research (Li et al., 2013, Li et al., 2016) and this study show that the studied high-pressure rocks and their veins are dominated by pyrite while minor chalcopyrite, and rare pyrrhotite, bornite, chalcocite, sphalerite, galena, arsenopyrite, cobalt-pentlandite and enargite contribute to a minor extent to the sulfur budget of the bulk ...

goethite (α-FeOOH),; akaganéite (β-FeOOH),; lepidocrocite (γ-FeOOH),; feroxyhyte (δ-FeOOH),; ferrihydrite (approx.), or, better recast as ; high-pressure pyrite-structured FeOOH. Once dehydration is triggered, this phase may form (< <).; schwertmannite (ideally () or + (,)); green rust (() + where A − is Cl − or 0.5SO 4 2−); Microbial degradation. Several species of bacteria ...

The high-pressure phase diagram of $mat{Si}{mat{O}}_{2}$ has been calculated using density-functional perturbation theory. We find that phase transitions of silica do not correspond to any observed seismic discontinuities within the Earth. We analyze the breakdown of close packing occurring in $mat{Si}{mat{O}}_{2}$ above …

2. 03/13/ 2017, Qingyang contributed a t alk "Discovery of pyrite-structured FeO 2 at high pressure" at Am erican Physical Society March Meeting, New Orleans, LA. In this talk, we showed recent experiment and simulation results on how hydrogen and oxygen elements are seperated and cycled in …

The Pyrite-Type High-Pressure Form of Silica Yasuhiro Kuwayama,1* Kei Hirose,1,2 Nagayoshi Sata,2 Yasuo Ohishi3 Silica (SiO 2) exhibits extensive polymorphism at elevated pressures. X-ray dif-fraction measurements showed that a high-pressure form with a pyrite-type structure, denser than other known silica phases, is stable above 268 giga-

A tetragonal high-pressure phase of PtAs 2 with I4/mmm symmetry was first discovered above 90 GPa by using first principle swarm intelligence structure search technique. The first order structure transition character of PtAs 2 from the ambient-pressure cubic pyrite phase to this tetragonal HP phase was confirmed by a large volume reduction of 8.1%.

What is Pyrite? Pyrite is a brass-yellow mineral with a bright metallic luster.It has a chemical composition of iron sulfide (FeS 2) and is the most common sulfide mineral.It forms at high and low temperatures and occurs, usually in small quantities, in igneous, metamorphic, and sedimentary rocks worldwide. Pyrite is so common that many geologists would consider it to be a ubiquitous mineral.

Thus, pyrite breakdown to pyrrhotite reactions operating during subduction metamorphism should produce oxidized Fe-depleted peak mineral assemblages in exhumed high-pressure rocks. Additionally, the low solubility of reduced sulfur species in rock-buffered systems suggests that sulfides may continue to persist in the slab (Evans et al., 2014 ...