pyrites

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pyrites

1. another name for pyrite
2. any of a number of other disulphides of metals, esp of copper and tin

Pyrites

 

pyrite ores consisting predominantly of sulfurous (sulfide) ore minerals. The composition of pyrites is dominated by iron sulfides (pyrite, pyrrhotite, marcasite). Also present are the sulfides of copper (chalcopyrite, bornite), zinc (sphalerite), and lead (galenite) and barium sulfate (barite). Pyrite deposits consist of massive as well as disseminated ores. These deposits have the shape of beds, lenses, stocks, and veins measuring up to 5,000 m long and 250 m thick; they occur at depths of as much as 2,000 m.

In terms of formation and occurrence, pyrites are closely linked to the basic and alkaline igneous rocks that issued onto the floor of ancient seas and formed extended ophiolite zones characteristic of the early stage of geosynclinal development. In the volcanic zones, pyrites form discontinuous chains measuring up to several thousand kilometers long. Pyrites arise in the late stage of volcanic cycles, when the eruption of the primary magma has been replaced by alkaline and acidic lavas, which are accompanied by the heavy venting of volcanic gaseous and liquid solutions. The solutions carry a large amount of metals that combine with the sulfurous sublimates and are deposited in the form of sulfides, creating the pyrites. That portion of the pyrites that arises along the seepage paths of the solutions through the volcanic rock forms hydrothermal metasomatic deposits. The other part of the mineral matter carried by the volcanic solutions reaches the floor of the sea and, in being deposited here, creates the volcanogenic sedimentary deposits of pyrites.

The accumulation of pyrites occurs over a long period of time, and in the early stages, predominantly the sulfurous iron compounds form, which are of limited practical interest. The pyrite deposits of copper, zinc, and lead arise in the later stages.

In the USSR the following pyrite deposits are known: Proterozoic (Karelia), Lower Paleozoic (Buriatia and Tuva), Middle and Upper Paleozoic (Urals and Caucasus), and Mesozoic and Cenozoic (Caucasus) deposits. Abroad, there are Proterozoic (Canada), Lower Paleozoic (Norway and Australia), Middle and Upper Paleozoic (Spain, Portugal), Mesozoic (Yugoslavia), and Cenozoic (Japan, Turkey, Greece, Cuba) deposits.

Pyrite deposits are an important source for obtaining copper, zinc, and lead and, in part, gold, silver, bismuth, cadmium, indium, barium, selenium, sulfur, and sulfuric acid.

REFERENCE

Genezis endogennykh rudnykh mestorozhdenii. Moscow, 1968.

V. I. SMIRNOV

References in periodicals archive ?
This important transgression is recorded in the La Gaita Formation as a marly interval 10 to 20 meters thick that contains a well preserved pyritized ammonite record.
4) are different, partly plain and very weakly phosphatized or pyritized, perhaps without any serious impact on the basin history.
The upper boundary is a distinct pyritized DS, the boundary between the higher-rank mesocyclites, and the Vesiku Beds of the Rootsikula Stage and the Soeginina Beds of the Paadla Stage.
Legend for Figs 3 and 6-8: 1, limestone (wackestone and packstone); 2, dolomitic argillaceous bioclastic limestone (wackestone and packstone); 3, argillaceous limestone (wackestone and packstone); 4, cryptocrystalline limestone (calcareous mudstone); 5, bioclastic limestone (packstone); 6, bioclastic limestone (grainstone); 7, calcareous marlstone; 8, calcareous marlstone with rare bioclastic material; 9, argillaceous marlstone; 10, dolomitized argillaceous marlstone; 11, pyritized discontinuity surface; 12, limestone nodule.
85 metre interval of the hole transected several zones of strongly altered and mineralized volcanic rocks similar to those encountered at the adjacent Taurus Deposit Results of composite assays from pyritized wall rock and vein stringer zones are given in the table below.
The specimens were found on bedding surfaces containing numerous muscovite flakes of different size, rare pyritized trace fossils, and sometimes tubes of Sabellidites.
The volcanic rocks have been intruded by several fine-grained diabase or diorite porphyry stocks, which have pyritized, silicified, kaolinized, and otherwise altered adjacent volcanics.
In the Mid Tyrrell Zone, saw cut samples from a gabbro-hosted quartz vein system with 3 vein orientations and heavily pyritized selvages assayed 117.
The Karinu Member consists mainly of rough-bedded skeletal packstone with tempestite interlayers, pyritized lithoclasts, rounded skeletons of stromatoporoids, and numerous pyritized discontinuity surfaces, indicating deposition in the inner part of the open shelf (IIIa) facies zone, from time to time influenced by storm waves and currents.
Thus they are distinct from polycrystalline pyrite aggregates of linear form (for example, pyritized worm burrows or linear pyrite concretions), which contain thousands of randomly oriented pyrite crystals, generally forming an overall cylindrical shape.