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Topic: Arsenopyrite

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  CONK! Encyclopedia: Arsenopyrite   (Site not responding. Last check: 2007-10-09)
Arsenopyrite may be referred to in older references as orthorhombic, but has been shown to be monoclinic.
Arsenopyrite also can contain significant amounts of gold and consequently is used by geologists as an indicator of potential gold bearing reefs.
Arsenopyrite is found in high temperature hydrothermal veins, in pegmatites, and in areas of contact metamorphism or metasomatism.
www.conk.com /search/encyclopedia.cgi?q=Arsenopyrite   (153 words)

 ARSENOPYRITE Chapter 21. Sulfides, arsenides, antimonides, and sulfosalts
Arsenopyrite is silver-white when freshly broken, is opaque, has a metallic luster which is commonly dulled by exposure, and has two commonly indistinct cleavages.
Arsenopyrite is an iron arsenic sulfide mineral and the major host for arsenic in the Franklin Marble.
Arsenopyrite also occurs in the margarite assemblage in the marble adjacent to the Sterling Hill orebody (Figures 21-6,  21-7, and 21-8); the assemblage is described under margarite (Dunn and Frondel, 1990).
simplethinking.com /dunn/ch21/arsenopyrite.stm   (678 words)

 Arsenopyrite -- Facts, Info, and Encyclopedia article   (Site not responding. Last check: 2007-10-09)
Arsenopyrite contains about 46% (A very poisonous metallic element that has three allotropic forms; arsenic and arsenic compounds are used as herbicides and insecticides and various alloys; found in arsenopyrite and orpiment and realgar) arsenic and is a principle ore of arsenic.
Arsenopyrite may be referred to in older references as (Click link for more info and facts about orthorhombic) orthorhombic, but has been shown to be monoclinic.
Arsenopyrite also can contain significant amounts of (A soft yellow malleable ductile (trivalent and univalent) metallic element; occurs mainly as nuggets in rocks and alluvial deposits; does not react with most chemicals but is attacked by chlorine and aqua regia) gold.
www.absoluteastronomy.com /encyclopedia/a/ar/arsenopyrite.htm   (239 words)

 Arsenopyrite   (Site not responding. Last check: 2007-10-09)
This sample of arsenopyrite is displayed in the Smithsonian Museum of Natural History.
Arsenopyrite is a sulfide mineral of arsenic and iron with the composition FeAsS.
This large arsenopyrite crystal formation is about 13x30 cm and is from Obira mine, Oita, Japan.
hyperphysics.phy-astr.gsu.edu /hbase/minerals/arsenopyrite.html   (83 words)

Massive arsenopyrite was found in the Trotter mine near the deposit of nickel arsenides described on page 29, and minute crystals were found there intermixed with desaulesite.
Arsenopyrite is also recorded from the Parker shaft, associated in one place with roeblingite, in another with quartz, pyroxene, and molybdenite.
Minute crystals of arsenopyrite were seen in a specimen of massive epidote and axinite from the Gooseberry iron mine, but there seems to be no record of its occurrence at Sterling Hill.
simplethinking.com /palache/arsenopyrite.stm   (854 words)

 Process for the recovery of noble metals from ore-concentrates - Patent 4786323
Arsenopyrites always contain silicates as gangue and depending on the type of ore, pyrite and carbonaceous materials such as graphite.
One proposal is the oxidizing pressure-leaching of arsenopyrites in an autoclave using NaOH, an oxygen-pressure of 10 bar, and a temperature of 100.degree.
The effect obtained by mechano-chemical structure changes of arsenopyrite concentrates is dependent on the concentration of the mineral components, on the operating conditions in the mill, and on the duration of milling, and it is therefore dependent on the expenditure of energy per ton of concentrate.
www.freepatentsonline.com /4786323.html   (4066 words)

 Ores and Metals
Fine-grained arsenopyrite is disseminated throughout the lithic bands but is less abundant in the quartz segregations.
Arsenopyrite is mainly inclusion-free but larger crystals enclose small, 10 - 30µm long, earlier arsenopyrite crystals, rare, 2 -10mm diameter sphalerite, chalcopyrite, pyrrhotite or mixed chalcopyrite-pyrrhotite blebs and 5 - 30µm, euhedral pyrite.
in arsenopyrite and as a 4 x 1µm gold 'fibre' in pyrite associated with 80 - 200µm diameter areas of 2 - 5µm diameter pyrrhotite and 1 -2µm diameter, irregular, pale blue phase that may be arsenopyrite or marcasite.
www.rosiehardman.com /goodprovenance/oresandmetals.htm   (1222 words)

 Title page for ETD etd-04212004-201854   (Site not responding. Last check: 2007-10-09)
Results indicate that the rate of arsenopyrite oxidation, represented by the rate law r = A(6.76 x 10-11) where the rate, r, is in mol/s and surface area, A, is in m2, is not significantly dependent on DO concentration.
Our results suggest that the rate determining step in arsenopyrite oxidation is determined by the attachment of oxygen at the anodic site in the mineral, and not the transfer of electrons from the cathodic site to oxygen, as is suggested for other sulfide minerals such as pyrite.
For example, at an abandoned arsenopyrite mine in Virginia, the pH of ground and surface waters is consistently between 4 and 7.
scholar.lib.vt.edu /theses/available/etd-04212004-201854   (259 words)

Arsenopyrite (white, high reflectance, top right) is the main phase; some is extensively fractured and cemented by chalcopyrite (yellow, centre left), which is altered to covelline and rimmed by brown stannite.
Arsenopyrite (white, left) is fractured and contains lath-shaped inclusions of native bismuth (cream, high reflectance, centre).
Euhedral arsenopyrite (white, high reflectance, centre) is extensively altered to covelline (blue, bottom left).
www.smenet.org /opaque-ore/Plate31.htm   (375 words)

 Chemical/biological process to oxidize multimetallic sulphide ores - Patent 4987081
The treatment process for multi-metallic ores such as arsenopyrite can be made to work rapidly and to as much as 98% sulphide oxidation, when the finely ground ore or concentrate is leached in agitated, air sparged tanks, with strains of three different bacteria, T. thiooxidans, T. ferrooxidans, and Leptospirillum ferrooxidans.
Other arsenopyrite as well as pyrite concentrate materials may also be suitable if they are finely ground to provide a large surface area as suspended solids in the final medium.
A culture grown on an arsenopyritic concentrate at a pH of 0.28 was grown successfully on ferrous iron at pH 0.9 and 2.3 as well as on elemental sulphur at pH 0.9.
www.freepatentsonline.com /4987081.html   (8576 words)

 [No title]   (Site not responding. Last check: 2007-10-09)
Therefore, it is desirable to separate the arsenopyrite from pyrite to reduce the cost of treating the barren or non-refractory pyrite and reduce the amount of unwanted material entering a refractory pre-treatment process.
Separation of pyrite and arsenopyrite by flotation using xanthates presents difficulties due to the fact that xanthates adsorb onto both these minerals as dixanthogen, which is not cation selective.
The decrease in recovery of arsenopyrite with an increase in depressant concentration was expected due to the greater thickness of the hydrophilic AsO4NH4Mg.6H2O layer being formed upon it, limiting the adsorption of xanthate, thus its flotability.
www.min-eng.com /protected/flot03ex/tapley.doc   (1777 words)

 Sterling Hill NJ Graphite, Arsenopyrite, Pyrite, Arsenic
Crystal of arsenopyrite from Sterling Hill, N. J., showing b{010}, q{210}, e {012}, n {101} and a pseudobase due to striation.
Crystal of arsenopyrite from Sterling Hill, N. J., equant, with q{210}, e{012}, and n{101}.
The graphite crystals are generally quite free but may be partly embedded in arsenopyrite, in arsenic or in diopside.
www.minsocam.org /msa/collectors_corner/arc/sterlinghillnj.htm   (2311 words)

 .html   (Site not responding. Last check: 2007-10-09)
Description: Arsenopyrite is formed in hydrothermal deposits, especially those formed at medium to high temperatures.
GREEN LAKE COUNTY: Small tabular to wedge-shaped crystals of arsenopyrite occur as an accessory mineral in a diabase dike approximately 2 kilometers SSW of Marquette (Hobbs, 1895).
MARATHON COUNTY: Falster (1987) notes that arsenopyrite occurs rarely as small crystals in the vugs of pegmatite bodies in the Wausau pluton.
www.uwrf.edu /~wc01/arsenopyrite.htm   (243 words)

 TRACE ANALYSIS OF INVISIBLE GOLD IN PYRITE AND ARSENOPYRITE   (Site not responding. Last check: 2007-10-09)
Auriferous pyrite and arsenopyrite were analysed at a voltage of 35 kV and current of 300-500 nA.
Light microscope photograph of etched pyrite and arsenopyrite with trace gold contents in ppm marked on the grains.
In the arsenopyrite grains of auriferous gold samples and concentrates, the gold content varies in the analyses from non detected to 700 ppm.
www.gsf.fi /info/posters/traceanalysis   (819 words)

 KINETICS OF ARSENOPYRITE OXIDATIVE DISSOLUTION BY OXYGEN   (Site not responding. Last check: 2007-10-09)
The macroscopic rate law for arsenopyrite oxidation as a function of dissolved oxygen is determined using multiple linear regression of log r vs. log P
Preliminary results indicate that arsenopyrite oxidation releases arsenite (subsequent oxidation to arsenate may occur), sulfate, and ferrous iron, though some oxidation to ferric iron is evident.
Sulfate is used as the main reaction progress variable for the oxidation reaction, as preliminary experiments showed that it exhibits conservative behavior once it is produced during the oxidation process.
gsa.confex.com /gsa/2003AM/finalprogram/abstract_60728.htm   (422 words)

 The mineral arsenopyrite
Arsenopyrite is the most prevalent mineral containing arsenic, and is thus a major
Arsenopyrite is famous for its distinctive crystals, and is a popular mineral among mineral collectors.
Much Arsenopyrite has also come from the gold-producing regions in the Sierra Nevada Mountains of California, namely in the Monitor-Mogule District.
www.minerals.net /mineral/sulfides/arsenopy/arsenopy.htm   (285 words)

 The chemistry of flotation activation and depression of iron-containing sulphide minerals
The initial oxidation of arsenopyrite surface produces ferric hydroxide and a realgar-like compound on the surface.
Flotation studies demonstrated that freshly ground arsenopyrite and pyrite are non-floatable in the absence of xanthate as a collector or strong iron-complexing agent: EDTA (hydrophilic).
Studies of the activation of sphalerite, arsenopyrite, pyrite and pyrrhotite by Cu(II) ions by using adsorption tests and cyclic voltammetry showed that the activation reactions between the sulphides and copper(II) depend on the solution pH.
epubl.luth.se /avslutade/0348-8373/70   (497 words)

 Search Results for arsenopyrite - Encyclopædia Britannica
It forms pale leek-green or grayish green to liver-brown aggregates of crystals, or pale green to pale grayish or brownish green...
Metallic arsenic forms when arsenopyrite is heated at 650°–700° C in the absence of air.
The arsenic in arsenopyrite and the arsenic impurities in other metal ores unite readily with oxygen when...
www.britannica.com /search?query=arsenopyrite&submit=Find&source=MWTAB   (272 words)

 Energy Citations Database (ECD) - Energy and Energy-Related Bibliographic Citations
The authors investigated the potential role of the three strains of Thiobacillus caldus (KU, BC13, and C-SH12) in arsenopyrite leaching in combination with a moderately thermophilic iron oxidizer, Sulfobacillus thermosulfidooxidans.
This result was similar to leaching arsenopyrite with a pure culture of S. thermosulfidooxidans in the presence of yeast extract.
The results showed that T. caldus KU was the most efficient at leaching arsenopyrite under the conditions tested, followed by BC13, and finally C-SH12.
www.osti.gov /energycitations/product.biblio.jsp?osti_id=318777   (243 words)

 Alan Guisewite's Mineral Collection Images: Miscellaneous Systematic Sulfides Page
Arsenopyrite shows an unusual habit (very elongated prisms) in this beautiful small cabinet piece from the Pachapaqui mining district, Peru.
An excellent miniature cluster of arsenopyrite stellate twins from the Quiruvilca District, Santiago de Chuco Province, La Libertad Department, Peru.
Gudmundite is the antimony analog (FeSbS) of arsenopyrite.
www.cs.cmu.edu /~adg/adg-pssuiimages.html   (5680 words)

 CR-Scientific: Catalog: Premium Mineral Specimens: Arsenopyrite and Fluorite - Shangbao Mine, Leiyang, Hunan, China
A choice Small-Cabinet specimen having large, lustrous, euhedral arsenopyrite crystals to 2 cm, with quartz, dolomite, and purple fluorite.
This specimen has two display faces; the front (shown in photo above) displays the arsenopyrite crystals, while the back of the piece (shown in this photo) displays more fluorite.
Some of the arsenopyrite crystals have rubbing or erosion, but it's difficult to tell if this is of natural origin or whether it took place during extraction of the specimen from the host rock.
www.crscientific.com /cr197-arsenopyrite.html   (183 words)

 Murdoch University Digital Theses
The nature and proportions of the products of the oxidation of arsenopyrite in aerated alkaline solutions have been studied using high pressure ion chromatography techniques that have shown that thiosulfate and a new species, monothioarsenate, are the main oxidation products of arsenopyrite apart from arsenate and sulfite.
A kinetic investigation of the oxidation of arsenopyrite with air or oxygen has shown that the initial rate of arsenopyrite oxidation is proportional to the concentration of dissolved oxygen.
A reaction mechanism for the oxidation of arsenopyrite has been proposed, which involves an anodic oxidation of the mineral involving hydroxyl ions coupled to a cathodic process for oxygen reduction which is partially controlled by mass transfer of dissolved oxygen to the mineral surface.
wwwlib.murdoch.edu.au /adt/browse/view/adt-MU20041201.152201   (387 words)

Arsenopyrite (FeAsS) is known as a major ore of arsenic.
The crystals have sharp acute angles that are a marked contrast from other sulfides that generally have only obtuse angles.
Arsenopyrite was previously thought to be orthorhombic, but recent analysis proves it as monoclinic.
www.sciencedaily.com /encyclopedia/pyrite   (415 words)

 Environmental & Earth Sciences is an Australasian company providing simple technical solutions for mining, groundwater ...   (Site not responding. Last check: 2007-10-09)
In the shoots or lodes, arsenopyrite was often readily distinguished by colour in the prill or primary ore and when dispatched to the surface was sent to the packing shed.
The arsenopyrite was hand picked and removed from the prill ore and left in piles on the surface.
At low pH, when the tailings are yellow or brown, arsenopyrite in the presence of water and air produces sulfuric acid, arsenate and jarosite (which is buttery yellow).
www.groundscience.com /solutionsnewsletter/solutions12/arsenic.html   (2569 words)

 Compositional variation of arsenopyrite and fluid evolution at the Ulsan deposit, southeastern Korea: a low-sulfidation ...
Isochemical contact metamorphism of an early skarn stage (stage I) is displayed by the presence of anhydrous Ca—Al—Mg skarn minerals at the contact between granite and recrystallized limestone.
Decreasing As contents in arsenopyrite from stages II to IV indicate a decrease in temperature or sulfur fugacity (or both) with time.
The various skarn-forming events and ore minerals from various stages are interpreted to have resulted from an evolutionary trend from hypersaline magmatic fluids during prograde skarn formation associated with Fe—As(—Ni) mineralization to low-salinity and low-temperature fluids during the retrograde skarn formation, associated with W—Cu—Zn mineralization.
www.nrc-cnrc.gc.ca /cisti/journals/mineral/56738-3.html   (735 words)

 minerological tests   (Site not responding. Last check: 2007-10-09)
The lead and arsenic sulfide and sulfate minerals (including arsenopyrite) found in Ironite are among the least soluble geochemical forms of these elements, making them markedly less available for systemic absorption upon ingestion than the much more soluble oxides (Davis et al., 1992 and 1996).
This coating with pyrite further inhibits the solubilization of arsenic from the arsenopyrite, thereby greatly reducing the potential for subsequent uptake of arsenic by plants or animals.
First, arsenopyrite by itself is a mineral form of arsenic with low solubility, and second, arsenopyrite is coated or encapsulated with an additional pyrite layer which further inhibits dissolution of the arsenic.
www.ironite.com /mineralogical_right.htm   (1385 words)

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