Pyrrhotite — Wikipédia

La pyrrhotite est une espèce minérale composée de sulfure de fer, de formule Fe 1-x S, 0 < x < 0,20, à structure type nickéline, dureté 3½-4½, de couleur jaune–bronze, noircissant à l''air. La pyrrhotite cristallise en lamelles {001}. Historique de la description et appellations ...

Pyrrhotite : références utiles

Partager. La pyrrhotite est un minéral présent à l''état naturel dans le sol. En raison de ses propriétés particulières (il s''oxyde au contact de l''air et de l''humidité, et il dégage de l''acide sulfurique qui attaque la pâte de ciment), la pyrrhotite ne doit en aucun cas et pour des raisons évidentes se retrouver dans l ...

Qu''est-ce que la pyrrhotite ? | Ce qu''il faut comprendre | ACQC

La pyrrhotite est une espèce minérale composée de sulfure de fer qui s''oxyde au contact de l''air et de l''humidité. Le minéral produit alors de l''acide sulfurique qui réagit avec le calcium et les aluminates du béton. La réaction entraine alors la fissuration et la désagrégation la fondation. Voilà pourquoi la pyrrhotite est si ...

My Pyrrhotite in Concrete Story | O''Reilly, Talbot & Okun

 · It turns out that pyrrhotite provides both of these stressors in abundance. Pyrrhotite is basically a chemically unstable form of iron pyrite, made up of iron and sulfur. When pyrrhotite is mined out of the ground and is exposed to air and moisture, it begins a long slow degradation reaction. As the pyrrhotite degradation progresses, the sulfur ...

Pyrrhotite Rejection at the Strathcona Mill

 · Currently Strathcona Mill receives ore mined from two main sources in the Sudbury area and produces two concentrate streams – a nickel-copper concentrate that is shipped to the Sudbury Smelter and a copper concentrate that is sent to the Fonderie Horne (Glencore Copper, Rouyn-Noranda). ... Pyrrhotite Rejection at the Strathcona Mill Reagent ...

pyrrhotite | mineral | Britannica

pyrrhotite, iron sulfide mineral (Fe1–xS) in the niccolite group; in it, the ratio of iron to sulfur atoms is variable but is usually slightly less than one. It commonly is found with pentlandite and other sulfides in silica-poor igneous rocks, as at Kongsberg, Nor.; Andreas-Berg, Ger.; Trentino, Italy; and Sudbury, Ont. The variety troilite, with a composition near that of iron sulfide (FeS ...


A superb Pyrrhotite from one of the world''s great localities. This fine specimen has two gorgeous hexagonal crystals, each over 1 cm across and thick, sitting on a matrix of black sphalerite and quartz. The brassy color and luster are unmatched, and there is even a hint of iridescence. Ex. Wendell E. Wilson Collection. © Rob Lavinsky & irocks

How do pyrite and pyrrhotite damage building foundations?

Pyrite and pyrrhotite are minerals known as iron sulfides. When iron sulfides are exposed to water and oxygen, a series of chemical reactions breaks down the iron sulfides and forms new minerals called sulfates. These sulfates take up more space than the original iron sulfides. As they grow, the new sulfate minerals push against the surrounding rock, causing it to swell and crack.

Crumbling Foundations

Crumbling Foundations. Upwards of 35,000 homes in a radius of Stafford Springs, Connecticut, are facing the potential for a failed concrete foundation due to the possible presence of a naturally occurring iron sulfide, pyrrhotite, in their concrete foundation. The concrete originated from the JJ Mottes Concrete Company in Stafford Springs ...

Pyrrhotite Mineral Specimens

Pyrrhotite with Quartz and Cassiterite Weilasituo Mine, Hexigten Banner, Chifeng City, Inner Mongolia, China Small Cabinet 8.9 x 6.6 x 4.0 cm (2 more images) Order Now. Details. SM20-401 Pyrrhotite Morro Velho Gold Mine, Nova Lima, Minas Gerais, Brazil Small Cabinet 9.1 x 7.1 x 3.3 cm (3 more images)

Influence of Pyrrhotite on the Corrosion of Mild Steel

 · As a result of the electrical conductivity of pyrrhotite, it was hypothesized that its presence in the corrosion product layer on a steel surface could lead to localized corrosion. Mild steel specimens (API 5L X65) were pretreated to form a pyrrhotite layer on the surface using high-temperature sulfidation in oil. The pretreated specimens were then exposed to a range of …

Cyanide Leaching and Decomposition of Pyrrhotite

 · The direct action of nonalkaline cyanide solutions on ferrous sulphides, which may be similar to their action on pyrrhotite, may be expressed as follows: FeS +7 KCN + H2O + O =. KCNS + K4Fe (CN)6 + 2 KOH. whereas in alkaline cyanide solutions this reaction is favored: 2 FeS + 2 KCN + 3 H2O + 3 O =. 2 KCNS + 2 Fe (OH)3.

The pyrrhotite case: the art of apportioning liability

 · Choice of materials is not an external event. The Court of Appeal dismissed the first argument. It found that the presence of pyrrhotite in the foundations was both a latent defect and a construction deficiency. This signified that the client could rely on the warranty of quality and the presumption of liability provided for under article 2118 ...

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The pentlandite, chalcopyrite and pyrrhotite from Enonkoski ore ground in a steel mill floated easily without a collector at low pH values of 3–5 ( Figure 1 ). The floatability of these three minerals was improved when the same ore was ground in a ceramic mill ( Figure 2 ).


What Is Pyrrhotite? Pyrrhotite is an iron sulfide mineral found in igneous and metamorphic rocks. Its chemical formula of Fe (1-x) S indicates that it is deficient in iron - which causes pyrrhotite to be slightly to strongly magnetic. After magnetite, pyrrhotite is the second-most-common magnetic mineral. ADVERTISEMENT Table of Contents

How To Cut Trapezoidal Thread | PTJ Blog

 · Code of trapezoidal thread: The code of trapezoidal thread is represented by the letter "Tr" and the nominal diameter × pitch, the unit is mm. The left-hand thread needs to be marked with "LH" after the size specification, and the right-hand thread does not need to be marked. Come directly to the important-CNC car G76 dry trapezoidal thread.

Pyrite and pyrrhotite

Pyrite and pyrrhotite. Pyrite is a mineral which is found in stone and produces sulfuric acid when it oxidizes upon contact with humidity and oxygen. When this phenomenon occurs under foundations, it can cause the heaving and cracking of the concrete slab. Pyrrhotite is a mineral species composed of iron sulfide and is of a bronze yellow color ...

Wisconsin Geological & Natural History Survey » Pyrrhotite

The pyrrhotite apparently formed during the metamorphism of the deposit (Mudrey, 1979). — Pyrrhotite is common at the Lynn massive sulfide deposit where it occurs with sphalerite, galena, chalcopyrite, silver and gold minerals (Kennedy, 1993). — Significant pyrrhotite occurs in sec. 30 T.36N. R.11E. (Dutton and Bradley, 1970).

Québec and the pyrrhotite problem An update

affected by pyrrhotite is undetermined but could very well lie between 375 million and 750 million dollars. For their part, homeowner representatives have said there may very well be as many as 4,000 to 5,000 homes affected by pyrrhotite, pushing the potential costs closer to …

Gold Pyrite, Pyrrhotite and Arsenopyrite Recovery

 · The recovery of gold associated with arsenopyrite and pyrrhotite has a similar response pattern from both collector and pH viewpoints as illustrated in Figures 8 and 9. It is sometimes desired to recover arsenopyrite away from pyrite. This is also an active area of flotation research and clearly the regulation of flotation pulp electrochemistry ...


Pyrrhotite is an iron sulfide (Fen S n+1) mineral with brass-yellow to copper-red color ( Fig. 1.44 ). The crystal system is monoclinic with hexagonal polytype, and it has no cleavage. The mineral depicts uneven fracture, metallic luster, and dark green to black streak. The specific gravity is around 4.6 and hardness is between 3.5 and 4.5.

How do pyrite and pyrrhotite damage building foundations?

This causes damage in two main ways: If pyrite or pyrrhotite are present in the rocks underneath buildings, the swelling can push on the foundation, walls, and basement floor of the building, causing cracks and other structural damage. In some cases, groundwater can then transport sulfates into the cracked foundation, causing further damage.

The Difference between Pyrite and Pyrrhoite

 · The difference between the two is that pyrrhotite has variable amounts of both iron and sulfur and pyrite does not. Pyrite is a constant FeS2 (one atom of iron and 2 atoms of sulfur). Pyrrhotite''s chemical composition is: Fe (1-x)S (x=0-0.17) Please don''t ask me to expound on that. Pyrrhotite is sometimes referred to as magnetic pyrite ...

Thread Milling | Vardex | Products | Vargus

The VARDEX Thread Milling Line offers an all-encompassing range of solutions. Thread Milling tools offer applications in multi-tooth, single-tooth for deep holes, and solid carbide tools. Click here to learn more about the Thread Milling system.

Pyrrhotite dans les fondations: le calvaire de Trois-Rivières

 · Pyrrhotite dans les fondations: le calvaire de Trois-Rivières. Par Stéphan Dussault. 06 avril 2011. Shutterstock . Plus de 500 familles devront refaire les fondations de leur maison neuve en raison d''un problème de gonflement du béton. Une facture moyenne de près de 200 000 $ par maison, que personne ne veut payer.

Metric Trapezoidal(ACME) Thread Dimensions & Specifications

0.5. 1. Formula for tap drill (round to closest available drill size): D1+ (0.05*p) D1 = minimum internal thread minor diameter, p = pitch. DIN 103 is similar to: JIS B 0217 Tolerance system for metric trapezoidal screw threads; ISO 2902/3/4; Chinese Standard GB/T5796. Metric …

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Acme Internal Thread Mills

 · Home > Products > Mill > Acme Internal Thread Mills . Latest News 2021 PRICE INCREASE. On September 1st 2021 Internal Tool had a 4% price increase, a 2021 Price file can be downloaded from our home page in excel and pdf format. We have not been able to upload the new price structure onto the individual item pages and have people working on it.

Pyrrhotite and Crumbling Concrete

 · Pyrrhotite weathering in the presence of moisture and air produces secondary minerals that expand, causing concrete to crack. This compromises the structural integrity and accelerates degradation with the increased infiltration of water and air. Crushed rock aggregate containing pyrrhotite is associated with a quarry in Willington, Connecticut.

External ISO Metric Trapezoidal Screw Threads Table Chart …

Trapezoidal threads are defined as follows by ISO standards: ISO 2901, ISO 2901, ISO 2903, ISO 2904 and ISO 103. Gages ISO metric trapezoidal screw thread are defined in the DIN 103-9 . TR 8 x 1.5 . where Tr designates a trapezoidal thread, 8 is the nominal diameter in millimeters, and 1.5 is the pitch in millimeters. When there is no suffix it ...

trapezoidal mill

Trapezoidal threads are defined as follows by ISO standards: ISO 2901, ISO 2901, ISO 2903, ISO 2904 and ISO 103. Gages ISO metric trapezoidal screw thread are defined in the DIN 103-9 . TR 8 x 1.5 . where Tr designates a trapezoidal thread, 8 is the nominal … Read More

Pyrrhotite Oxidation

Pyrrhotite exists under multiple polytype crystal symmetries of the type Fe(1-x)S; reactions of one type: 3Fe7S8 +38O2 = 7Fe3O4 + 24SO2 (>300C) Fe3O4 = Fe2O3 +FeO (>1500C) (unknown) 6 years ago (unknown) 6 years ago. Like. Fe (1-x) S as fine powder could react with SO2 gas over 150 centigrade in aerated environment at 0.6 atm. Try on dryer plate.

Assessing Pyrrhotite in Concrete | NIST

 · Pyrrhotite (Fe1-xS, where x = 0 – 0.2) is a common sulfide mineral exhibiting a brownish-bronze color with a metallic luster. Physical properties include a hardness of 4 on the Mohs scale, a specific gravity ranging between 4.58 and 4.65 and is magnetic, but with varying intensity depending upon the iron content.


Pyrrhotite is an iron sulfide mineral with the formula Fe (1-x) S (x = 0 to 0.2). It is a nonstoichiometric variant of FeS, the mineral known as troilite.Pyrrhotite is also called magnetic pyrite, because the color is similar to pyrite and it is weakly magnetic.The magnetism decreases as the iron content increases, and troilite is non-magnetic. [page needed]

Pyrrhotite: The mineral pyrrhotite information and pictures

Pyrrhotite is commonly pseudomorphed by Pyrite, with complete replacement of the Pyrhottite by sparkling Pyrite crystals. Pyrrhotite is named from the Greek word pyrrhos, which means "color of fire". This is despite the fact that the usual color of Pyrrhotite is a bronze color rather than red; however its tarnish may have hints of sparkling red.

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