Journal ArticleDOI
A general equation for estimating Fe3+ concentrations in ferromagnesian silicates and oxides from microprobe analyses, using stoichiometric criteria
TLDR
In this article, a simple general equation is presented for estimating the Fe 3 § concentrations in ferromagnesian oxide and silicate minerals from microprobe analyses, assuming that iron is the only element present with variable valency.Abstract:
A simple general equation is presented for estimating the Fe 3 § concentrations in ferromagnesian oxide and silicate minerals from microprobe analyses. The equation has been derived using stoichiometric criteria assuming that iron is the only element present with variable valency and that oxygen is the only anion. In general, the number of Fe 3 + ions per X oxygens in the mineral formula, F, is given by; F = 2X(1 - T/S) where T is the ideal number of cations per formula unit, and S is the observed cation total per X oxygens calculated assuming all iron to be Fe 2 § Minerals for which this equation is appropriate include pyralspite and ugrandite garnet, aluminate spinel, magnetite, pyroxene, sapphirine and ilmenite. The equation cannot be used for minerals with cation vacancies (e.g. micas, maghemite) unless, as in the case of amphiboles, the number of ions of a subset of elements in the formula can be fixed. Variants of the above equation are presented for some of the numerous published schemes for the recalculation of amphibole formulae. The equation is also inappropriate for minerals showing SP += 4H § substitution (e.g. staurolite, hydrogarnet), minerals containing an unknown proportion of an unanalysed element other than oxygen (e.g. boron-bearing kornerupine) and minerals containing two or more elements with variable valency.read more
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Journal ArticleDOI
Nomenclature of amphiboles Report of the Subcommittee on Amphiboles of the International Mineralogical Association Commission on New Minerals and Mineral Names;Nomenclature of amphiboles Report of the Subcommittee on Amphiboles of the International Mineralogical Association Commission on New Minerals and Mineral Names
Bernard Elgey Leake,Alan R. Woolley,C. E. S. Arps,William D. Birch,M. C. Gilbert,Joel D. Grice,Ec. Hawthorne,A. Kato,Hanan J. Kisch,V. G. Krivovichev,K. Linthout,J. Laird,Joseph A. Mandarino,W. V. Maresch,Ernest H. Nickel,N. M. S. Rock,John C. Schumacher,D. C. Smith,Nicholas C.N. Stephenson,Luciano Ungaretti,Eric J.W. Whittaker,G. Youzhi +21 more
TL;DR: The International Mineralogical Association's approved amphibole nomenclature has been revised to simplify it, make it more consistent with divisions generally at 50%, define prefixes and modifiers more precisely, and include new amphibole species discovered and named since 1978, when the previous scheme was approved.
Journal ArticleDOI
Nomenclature of amphiboles; report of the subcommittee on amphiboles of the International Mineralogical Association, Commission on New Minerals and Mineral Names
TL;DR: The International Mineralogical Association's approved amphibole nomenclature has been revised to simplify it, make it more consistent with divisions generally at 50%, define prefixes and modifiers more precisely, and include new amphibole species discovered and named since 1978, when the previous scheme was approved.
Journal ArticleDOI
Activity–composition relations for the calculation of partial melting equilibria in metabasic rocks
Eleanor C. R. Green,Richard White,Johann F.A. Diener,Roger Powell,Tim Holland,Richard M. Palin +5 more
TL;DR: In this paper, a set of thermodynamic models for partial melting equilibria for metabasic rocks is presented, consisting of new activity composition relations combined with end-member thermodynamic properties from the Holland & Powell dataset.
Journal ArticleDOI
The origin of cratonic diamonds — Constraints from mineral inclusions
Thomas Stachel,Jeff W. Harris +1 more
TL;DR: The origin of cratonic diamonds is reviewed on the basis of nearly 5000 analyses of silicate, oxide and sulphide inclusions in diamonds as mentioned in this paper, and compositional fields are defined for common minerals of the peridotitic, eclogitic and websteritic inclusion suites.
Journal ArticleDOI
High-Pressure Granulites (Retrograded Eclogites) from the Hengshan Complex, North China Craton: Petrology and Tectonic Implications
TL;DR: In this paper, the early isothermal decompressional clockwise P-T path for the Hengshan prograde assemblage (M1) is preserved only in the high pressure granulites.
References
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Journal ArticleDOI
Origin of Basalt Magmas: An Experimental Study of Natural and Synthetic Rock Systems
H. S. Yoder,C. E. Tilley +1 more
Journal ArticleDOI
The iron-titanium oxides of salic volcanic rocks and their associated ferromagnesian silicates
TL;DR: In this article, the coexisting microphenocrysts of magnetite and ilmenite together with the ferromagnesian silicates in salic volcanic rocks have been analyzed with the electron microprobe.
Journal ArticleDOI
Omphacite in Californian metamorphic rocks
TL;DR: Omphacite is a common mineral in greenstones, metasediments and related Franciscan rocks of the glaucophane schist facies as discussed by the authors, and it also occurs in late veins cutting amphibolites, glaucaphane schists, eclogites, greenstones and occasionally metagraywackes.