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The ore minerals and their intergrowths

01 Jan 1969-
TL;DR: Both the man and his volume has become legends in the authors' time’s time” (Econ. Geol., vol. 66, 1971, Reviews)
Abstract: (partial) Introduction to the general section Intergrowths of the ore minerals Genetic systematics of ore deposits Meteorites Magmatic sequence Sedimentary sequence Metamorphic sequence Ore textures - principles of the classification of the ore intergrowths The fabric properties considered from a purely geometric point of view Genetic fabric types The relationship of ore textures to industrial minerals and benefication problems Descriptive section Elements and intermetallic compounds Alloy-like compounds and tellurides Common sulphides and 'sulphosalts' Oxidic ore minerals Gangue mineral and non-opaque oxide ore minerals
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Journal ArticleDOI
TL;DR: In this article, the role of volume change and evolution of porosity is explored both from natural microtextures and new experiments on model replacement reactions in simple salts, and it is shown that porosity development is often a consequence of mineral replacement processes, irrespective of the relative molar volumes of parent and product solid phases.
Abstract: Mineral replacement reactions take place primarily by dissolution-reprecipitation processes. Processes such as cation exchange, chemical weathering, deuteric alteration, leaching, pseudomorphism, metasomatism, diagenesis and metamorphism are all linked by common features in which one mineral or mineral assemblage is replaced by a more stable assemblage. The aim of this paper is to review some of these aspects of mineral replacement and to demonstrate the textural features they have in common, in order to emphasize the similarities in the underlying microscopic mechanisms. The role of volume change and evolution of porosity is explored both from natural microtextures and new experiments on model replacement reactions in simple salts. It is shown that the development of porosity is often a consequence of mineral replacement processes, irrespective of the relative molar volumes of parent and product solid phases. The key issue is the relative solubility of the phases in the fluid phase. Concepts such as coupled dissolution-precipitation, and autocatalysis are important in understanding these processes. Some consequences of porosity generation for metamorphic fluid flow as well as subsequent crystal growth are also discussed.

954 citations


Cites background from "The ore minerals and their intergro..."

  • ...For example, Ramdohr (1980) describes typical sulphide textures where many small inclusions of sulphate minerals attest to a later-stage infilling of pores....

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  • ...In all cases the reactions are the result of fluids penetrating the primary ores, and virtually every sulphide mineral can be replaced by another (Ramdohr, 1980; Roberts and Travis, 1986)....

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  • ...penetrating the primary ores, and virtually every sulphide mineral can be replaced by another (Ramdohr, 1980; Roberts and Travis, 1986)....

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Journal ArticleDOI
TL;DR: In this article, the stability of colloidal, iron monosulfide suspensions with ionic strengths typical of marine and lacustrine waters was evaluated using DLVO theory and a term was included to account for the ferrimagnetic properties of greigite.

639 citations

Journal ArticleDOI
TL;DR: In this paper, it was shown that acid volatile sulfide (AVS) is not equivalent to FeS and solid FeS phases have rarely been identified in marine sediments.

561 citations


Cites background from "The ore minerals and their intergro..."

  • ...As shown by Rickard (1995) the mechanism of the reaction permits the estimate of the rate of FeS formation in systems where Fe(II) is ratelimiting....

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Journal ArticleDOI
TL;DR: The formation of magnetite is driven by the extraction of silica from the Fe3Si2O5(OH)4 component of serpentine, producing extremely reducing conditions as evinced by the rare iron alloys that partially serpentinized peridotites contain this paper.
Abstract: Serpentinites have the lowest silica activity of common crustal rocks. At the serpentinization front, where olivine, serpentine, and brucite are present, silica activities (relative to quartz) are of the order of 10 � 2� 5 to 10 � 5 , depending on the temperature. Here we argue that this low silica activity is the critical property that produces the unusual geochemical environments characteristic of serpentinization.The formation of magnetite is driven by the extraction of silica from the Fe3Si2O5(OH)4 component of serpentine, producing extremely reducing conditions as evinced by the rare iron alloys that partially serpentinized peridotites contain. The incongruent dissolution of diopside to form Ca 2þ , serpentine, and silica becomes increasingly favored at lowerT, producing the alkalic fluids characteristic of serpentinites.The interaction of these fluids with adjacent rocks produces rodingites, and we argue that desilication is also part of the rodingite-forming process.The low silica activity also explains the occurrence of low-silica minerals such as hydrogrossular, andradite, jadeite, diaspore, and corundum in serpentinites or rocks adjacent to serpentinites. The tendency for silica activity to decrease with decreasing temperature means that the presence of certain minerals in serpentinites can be used as indicators of the temperature of serpentinization. These include, with decreasing temperature, diopside, andradite and diaspore. Because the assemblage serpentine þ brucite marks the lowest silica activity reached in most serpentinites, the presence and distribution of brucite, which commonly is a cryptic phase in serpentinites, is critical to interpreting the processes that lead to the hydration of any given serpentinite.

439 citations

Journal ArticleDOI
TL;DR: In this paper, electron microprobe analyses of minor and trace elements in magnetite and hematite from a range of mineral deposit types (IOCG), Kiruna apatite, magnetite, chromite, and spinel series, and ulvospinel as a result of divalent, trivalent, and tetravalent cation substitutions) are used to construct discriminant diagrams that separate different styles of mineralization.
Abstract: Magnetite and hematite are common minerals in a range of mineral deposit types. These minerals form partial to complete solid solutions with magnetite, chromite, and spinel series, and ulvospinel as a result of divalent, trivalent, and tetravalent cation substitutions. Electron microprobe analyses of minor and trace elements in magnetite and hematite from a range of mineral deposit types (iron oxide-copper-gold (IOCG), Kiruna apatite–magnetite, banded iron formation (BIF), porphyry Cu, Fe-Cu skarn, Fe-Ti, V, Cr, Ni-Cu-PGE, Cu-Zn-Pb volcanogenic massive sulfide (VMS) and Archean Au-Cu porphyry and Opemiska Cu veins) show compositional differences that can be related to deposit types, and are used to construct discriminant diagrams that separate different styles of mineralization. The Ni + Cr vs. Si + Mg diagram can be used to isolate Ni-Cu-PGE, and Cr deposits from other deposit types. Similarly, the Al/(Zn + Ca) vs. Cu/(Si + Ca) diagram can be used to separate Cu-Zn-Pb VMS deposits from other deposit types. Samples plotting outside the Ni-Cu-PGE and Cu-Zn-Pb VMS fields are discriminated using the Ni/(Cr + Mn) vs. Ti + V or Ca + Al + Mn vs. Ti + V diagrams that discriminate for IOCG, Kiruna, porphyry Cu, BIF, skarn, Fe-Ti, and V deposits.

400 citations