Die Struktur von Karinthin und einer barroisitischen Hornblende

Heritsch, Haymo; Paulitsch, P.; Walitzi, E. M.

doi:10.1007/bf01128124

Cited by 22 publications

(4 citation statements)

References 7 publications

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“…No apparent correlation of b or c A, or 13 with composition is readily indicated. The hornblendes do have a similar crystal structure relationship to four of the six hornblendes investigated by Heritsch, Paulitsch, and Walitzi (1957), Heritsch, Bertoldi, and Walitzi (1959), Heritsch and Kahler (1959), and Heritsch and Reichert (1959) and tabulated by Deer, Howie, and Zussman (1963, p. 267). Densities, both measured and calculated (table 5), agree fairly well and are within 0.02 of one another. The lowest hornblende densities belong to those in the hornblendites and the highest to those in the hornblende gneiss.…”

Section: Optical Propertiessupporting

confidence: 54%

Hornblendes from a region of high-grade metamorphism, Front Range, Colorado

Gable¹,

Smith²

1975

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Calcic hornblendes from Precambrian metamorphic and igneous terranes in the central Front Range, Colo., were subjected to a sillimanite-grade metamorphism and have compositions that are more dependent on host-rock mineral a~semblages than on host-rock chemical composition. The partitioning of the mafic oxides Mg, Fe+ 2 , Fe+ 3 , and Mn between biotite and hornblende is necessary in relating the total mineral assemblage to the composition of the host rocks. Orderly distribution of the mafic oxides between biotite and hornblende yields rather consistent distribution patterns, and these patterns appear to relate to the regional metamorphism. Fe+ 3 in the metamorphic host rocks controls, though perhaps imperfectly, the Mg content in hornblende, whereas Fe+ 3 in igneous host rocks only exerts partial control over Mg in accompanying hornblende. In general, oxidation-reduction ratios in the igneous hornblendes increase with increases in Fe+ 3 but decrease in metamorphic hornblendes with increasing Fe+ 3 ; FIGURE 1 (facing page). -Generalized geologic map of a part of the Front Range, Boulder, Gilpin, and Jefferson Counties, Colo.

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Section: Optical Propertiessupporting

confidence: 54%

Hornblendes from a region of high-grade metamorphism, Front Range, Colorado

Gable¹,

Smith²

1975

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“…Early studies of aluminous amphiboles were done with two-dimensional diffraction data. The authors assumed disordered site-populations at the T(1) and T(2) sites in the C2/m amphibole structure (Heritsch & Kahler 1960, Heritsch & Reichert 1960, Heritsch et al 1957, Trojer & Walitzi 1965. Papike et al (1969) first showed that the <T(1)-O> distances are longer than the <T(2)-O> distances in [4] Al-bearing amphiboles, and Hawthorne & Grundy (1973a, b) and Robinson et al (1973) proposed relations between <T(1)-O> and <T(2)-O> distances and [4] Al site-populations in C2/m amphiboles.…”

Section: Review Of Our State Of Knowledgementioning

confidence: 99%

THE CRYSTAL CHEMISTRY OF Al-RICH AMPHIBOLES: SADANAGAITE AND POTASSIC-FERRISADANAGAITE

Hawthorne

Harlow

2008

The Canadian Mineralogist

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The crystal structures of magnesiosadanagaite (MS) from Mogok, Myanmar, monoclinic, a 9.857(2), b 17.899(4), c 5.318(1) Å, b 105.36(1)°, V 904.74(8) Å 3 , C2/m, Z = 2, and potassic-ferrisadanagaite (FS) from the Ilmen alkaline massif, South Urals, Russia, a 9.9257(4), b 18.0917(7), c 5.3709(2) Å, b 105.19(1)°, V 930.75(2) Å 3 , C2/m, Z = 2, have been refined to R values of ~3% using single-crystal MoKa X-ray data. The crystals used in the collection of the intensity data were subsequently analyzed by electron-microprobe techniques, leading to the following compositions: MS: (Na 0.82 K 0.17) (Ca 1.95 Na 0.05) (Mg 3.36 Fe 2+ 0.23 Al 1.20 Cr 3+ 0.07 Ti 4+ 0.16) (Si 5.47 Al 2.53) O 22 [(OH) 1.58 F 0.42 ]; FS: (Na 0.31 K 0.62) (Ca 1.72 Na 0.28) (Mg 0.56 Fe 2+ 2.12 Mn 2+ 0.26 Zn 0.02 Al 0.72 Fe 3+ 1.07 Ti 4+ 0.21) (Si 5.24 Al 2.76) O 22 [(OH) 1.70 F 0.30 ]. Site populations were assigned from the results of site-scattering refinement and stereochemical analysis, taking into account the unit formula determined for each crystal. The distances, 1.678 and 1.684 Å, indicate that [4] Al is strongly ordered at the T(1) site in each crystal, but the distances, 1.648 and 1.655 Å, indicate significant Al at the T(2) site. The Fe 2+ and Fe 3+ contents in each crystal were assigned from the distances. The A(2) and A(m) sites are occupied by Na and (Na,K), respectively, in crystal MS, and by Na and K, respectively, in crystal FS. Both amphiboles show SRO (short-range order) of species at the M(4), O(3), A(m) and A(2) sites, and the relative abundances of these arrangements were assigned.

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“…It is to be noted that this internal inconsistency occurs only in work which has been done or reported hitherto using the conventional /-cell with fl obtuse. The C-cell with fl obtuse has its z-axis in the same direction as the /-cell with fl acute, so that there is no discrepancy from this source in the work of Heritsch, Paulitsch & Walitzi (1957) who used both of these directly comparable conventions. Nevertheless we consider that the continued use of an acute fl-angle is likely to lead to increasing misunderstanding and confusion for future workers.…”

Section: The Angle Fl and The Sense Of The Z-axismentioning

confidence: 99%

“…Warren (1930) kept fi acute but defined it as XOZ, and this contravention of currently accepted crystallographic usage was perpetuated by Whittaker (1949), describing crocidolite, and by Heritsch, Paulitsch & Walitzi (1957), describing hornblendes, in order to facilitate direct comparison with Warren's work. In Structure Reports (1949) the fl angle for crocidolite was converted to the conventional obtuse value, but no allowance was made for the fact that this involved a change in the sense of the z-axis, so that the atomic z-coordinates should have been appropriately modified.…”

Section: The Angle Fl and The Sense Of The Z-axismentioning

confidence: 99%