Structural control of the chlorine content of OH-bearing silicates (micas and amphiboles)

Volfinger, M.; Robert, Jean-Louis; Vielzeuf, Daniel; Neiva, A.M.R.

doi:10.1016/0016-7037(85)90189-9

Cited by 181 publications

(56 citation statements)

References 12 publications

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“…The relationship between chlorine contents and bulk-amphibole composition for the potassium-rich calcic amphiboles is illustrated in Figure 2. There is a slight tendency for Cl content to increase with increasing IV Al and total Fe, comparable to trends observed by others (Makino et al 1993, Morrison 1991, Oberti et al 1993, Volfinger et al 1985.…”

Section: Potassium-rich Amphiboles Associated With Alkali-chloride Mesupporting

confidence: 89%

The Diversity and Occurrence of Potassium-Dominant Amphiboles

Mazdab

2003

The Canadian Mineralogist

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Currently, the Commission on New Minerals and Mineral Names (CNMMN) of the International Mineralogical Association (IMA) recognizes seven amphibole species where potassium is the dominant A-site cation. These include potassic-ferrisadanagaite, potassic-fluororichterite, potassic-magnesiosadanagaite, potassicpargasite, potassicsadanagaite, potassic-chloropargasite and potassicleakeite. However, as a result of an evaluation of compositions of Cl-bearing amphibole samples from iron-oxide-rich ore systems and a comparison with data in the reviewed literature, fourteen additional naturally occurring potassium-dominant amphiboles can be justified from selected published chemical data using recommended protocols for normalization. In keeping with accepted amphibole nomenclature, these new amphibole end-members would be "potassichastingsite", "potassicchlorohastingsite", "potassic-ferropargasite", "potassic-chloro-ferropargasite", "potassic-aluminosadanagaite", "potassicchlorosadanagaite", "potassic-chloro-ferro-edenite", "potassicrichterite", "potassic-ferrorichterite", "potassic-fluoromagnesiokatophorite", "potassic-ferritaramite", "potassic-magnesio-arfvedsonite", "potassic-fluoro-magnesio-arfvedsonite" and "potassickornite". In several of the potassium-dominant amphiboles evaluated, chlorine is an important OH-site component, even where it is not the dominant anion, and the optional modifier "chlorian" is appropriate. Indeed, various species of both Cl-rich and K-rich ferropargasite and hastingsite (both sensu lato) are characteristic amphiboles of certain iron-oxide-rich hydrothermal systems associated with alkali-chloride metasomatism. At one locality, another new chlorine-dominant amphibole, although lower in potassium, seems present: potassian "chlorosadanagaite". In addition to mineralization related to hypersaline fluids, the "potassic-" amphiboles are otherwise widespread in diverse igneous, metamorphic, and metasomatic environments. It is hence desirable and justifiable, notably for those cases where results of chemical analyses are accompanied by data on crystallographic and physical properties, to confer species status to these amphiboles. chlore, provenant de systèmes minéralisés en oxydes de fer, et d'une comparaison avec les données dans la littérature, on peut justifier quatorze nouvelles espèces d'amphibole à dominance de potassium en utilisant les protocoles recommandés pour la normalisation. Ceux-ci se nommeraient, en termes du schéma de nomenclature accepté, "potassichastingsite", "potassicchlorohastingsite", "potassic-ferropargasite", "potassic-chloro-ferropargasite", "potassic-aluminosadanagaïte", "potassicchlorosadanagaïte", "potassic-chloro-ferro-edenite", "potassicrichterite", "potassic-ferrorichterite", "potassic-fluoromagnésiokatophorite", "potassic-ferritaramite", "potassic-magnésio-arfvedsonite", "potassic-fluoro-magnésio-arfvedsonite" et "potassickornite". Dans plusieurs cas, le chlore est un composant important du site OH, même où il n'y est pas l'anion prédominant, et le qualifi...

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Section: Potassium-rich Amphiboles Associated With Alkali-chloride Mesupporting

confidence: 89%

The Diversity and Occurrence of Potassium-Dominant Amphiboles

Mazdab

2003

The Canadian Mineralogist

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“…For a choice of ionic radii from the table proposed by Shannon andPrewitt (1969, 1970), the coordination numbers of the anions are o (7) 3.59 0(5)x2 3.681 (7) 2,76 0(5)x2 3,400(4) 3.17 0(6)x2 3,340 (9) 2.76 0(6)x2 3,070(5) 3.17 0 (7) 3,456(13) 2,74 0(7) 3,058(6) 3.15 A(2/m) 3,751 (10) 2.95 A(2/m) 3.284(4) 3.36 o Ionic radius(A):r(O)=1.38 for fourfold coordination, r(O)=1.36 for threeforld coordination, <,'>^=1.57=0.735r(K)+0.265r(Na) for the A site (Shannon and Prewitt;,1970, r(CI)=1.79 (estimated in this work). required (Volfinger et al, 1985). O in the O(3A) site bonds to cations in three octahedral sites (2M(I) and M(3)) and to thc H cation.…”

Section: Resultsmentioning

confidence: 99%

“…A high Cl-content is observed in Fe 2+ rich mica (biotite or annite), whereas phlogopite, the Mg end-member, contains little C1. Volfinger et al (1985) interpreted the relation between Fe 2+ and the Cl-content in terms of the structural control, and extended the model from micas to amphiboles. Calcic amphiboles differ from micas in the configuration of (Mg, Fe 2+) and (OH, C1) sites.…”

Section: Resultsmentioning

confidence: 99%

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Effect of chlorine on the crystal structure of a chlorine-rich hastingsite

Makino¹

1993

Mineral. mag.

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The structure refinement of a hastingsite (Cl 0.91 p.f.u.) from West Ongul Island, Ltitzow-Holm Bay, East Antarctica, has been carried out in order to characterise the effect of CI on the crystal structure.The composition of the Cl-rich hastingsite is Ko 69Nao 26Cal 99Mgl 09Fe2+2 71Fe3+0 92Mn0.~4Ti0 10-A12.31Sis.s3022OH0.99C10.91F0.10 with unit cell parameters a 9.962(3), b 18.283i7), c 5.572(1) )~ and [3 104.87(3) ~ .In the Cl-rich hastingsite, A1, Fe 3 § and Ti occupy only the M(2) site, and Fe 2 § strongly prefers the M(1) and M(3) sites to the M(2) site with respect to Mg. The Mg-Fe 2 § distribution suggests that the Mg-CI avoidance is realised in the intracrystalline exchange reaction among the octahedral sites in the Cl-rich hastingsite. The individual position of CI and OH was refined and the effective ionic radius of C1 in fourfold coordination is determined as 1.79 A. Substitution of C1 for OH expands the sizes of the M(1) and M(3) sites and extends the double chains in comparison with hydroxy calcic amphiboles. C1 especially, is close to the 0(6) and 0(7) oxygens beyond the minimum distance calculated from effective ionic radii. Therefore, the Cl-rich hastingsite is considered to be deformed locally by C1.

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“…The higher Cl contents in the K-feldspar granite relative to the syenite indicate more contributions from the decomposition of chlorine mineral, such as amphibole. Amphibole is apt to decomposition and release Cl into the fluids (Volfinger et al, 1985;Zhang et al, 2012). Melting of the source which has been metasomated by Clenriched fluid may result in high Cl content magma.…”

Section: Origin Of the Haiyang A-type Granite Complexmentioning

confidence: 99%