The choice of axes in the amphiboles

Whittaker, E. J. W.; Zussman, J.

doi:10.1107/s0365110x61000097

Cited by 10 publications

(4 citation statements)

References 5 publications

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“…As stated above, relative to their structures, the C 2/c lattice setting of clinopyroxenes is parallel to the I 2/m lattice of clinoamphiboles, which coincides with the Tschermak setting. Whittaker and Zussman (1961) Beyond the clinoamphiboles, inconsistencies in settings may still exist in depictions of other minerals.…”

Section: Discussionmentioning

confidence: 99%

“…Outside of the (110) cleavage face in the back, the crystal is bounded by growth faces and clinodome is terminated by (1-1-1) and (11-1). Figure 10: Depiction of the relationship between the centering of the C monoclinic lattice in bold, and the I monoclinic lattice shaded in grey with axes denoted by subscripts for the C and I lattice settings, modified after Whittaker and Zussman (1961). This is a preprint, the final version is subject to change, of the American Mineralogist (MSA) Cite as Authors (Year) Title.…”

Section: Figure Captionsmentioning

confidence: 99%

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EXCALIBR to EXCELIBR and the Optical Orientation of Minerals: Correcting the Optical Orientation of Clinoamphiboles

Steven

Gunter

2020

msam

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The crystallographic orientation of C 2/m amphiboles has been depicted incorrectly since the standardization of amphiboles in C 2/m. Texts citing the early optical work on amphiboles reference structures drawn in the I 2/m cell, for which the optical orientation is correct. When C 2/m became the standard space group, the optical orientation, (hkl), and crystallographic axes depicted in crystal form drawings were never revised. Using the methods outlined by Gunter and Twamley (2001) combined X-ray and optical methods on single crystals of amphiboles reveal the discrepancy between axes. In the correct orientation of a typical C 2/m amphibole, the physical optical orientation should have never changed from its position outlined in the Tschermak setting as shown in Ford and Dana (1932), however, the crystallographic axes and (hkl) should have changed to accommodate the difference between the I 2/m cell and the C 2/m cell. This error may perpetuate a misunderstanding between the crystallographic setting and optical orientation of clinoamphiboles, which is an important relationship for orientation-dependent analytical methods. Enclosed in this study is the correction of crystallographic axes for crystal form drawings for C 2/m amphiboles, along with an outline of methodology and updates to the spreadsheet EXCELIBR. The methods applied in this study utilize relationships between crystallographic and optical vectors and include an addendum to those presented by Gunter and Twamley (2001), which is applicable to arbitrary reference positions on spindle stages.

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Section: Discussionmentioning

confidence: 99%

Section: Figure Captionsmentioning

confidence: 99%

EXCALIBR to EXCELIBR and the Optical Orientation of Minerals: Correcting the Optical Orientation of Clinoamphiboles

Steven

Gunter

2020

msam

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“…Whittaker ( 1961 &1962) described a second variant recognized by its resistance to sodium fluoride inhibition (Elf) and suggested that the gene was allelic to the ElU and Ela genes. Observation of predicted homozygotes for the Elf gene soon followed and additional family data fitted the allelic hypothesis (Liddell et al, 1963;Whittaker, 1964;Griffiths et al, 1966;Simpson & Kalow, 1965). Moderate apnea has been observed in some individuals with only the fluoride-resistant enzyme (Lehmann et al, 1963;Simpson, 1967).…”

Section: Ckolinesterasementioning

confidence: 95%

Genetics of Esterases in Man

Simpson

1968

Annals of the New York Academy of Sciences

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“…The difficulties arise partly from the prevalence of twinning on (100), and partly from certain approximate equalities between various parameters of the clino-amphibole lattice. Some of these have been discussed by Whittaker & Zussman (1961), and indexing is here kept entirely in terms of the setting C2/m for the space group of the clino-amphiboles.…”

Section: Electron Diffraction Patterns Of Amphibolementioning

confidence: 99%

High-resolution electron microscopy and diffraction studies of fibrous amphiboles

Hutchison¹,

Irusteta²,

Whittaker³

1975

Acta Cryst Sect A

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Fibrous specimens of tremolite, amosite, crocidolite and anthophyllite have been studied by electron diffraction and high-resolution microscopy. Amosite (and to a lesser extent crocidolite) are shown to be subject to frequent twinning on (100) leading to stacking disorder, and an explanation is provided of previously supposed anomalies in their diffraction patterns [Chisholm (1973), J. Mater. Sci. 8, [475][476][477][478][479][480][481][482][483]. Tremolite is sensibly free from these defects and this is explained in terms of crystal chemistry. The presence of Wadsley defects of the type suggested by Chisholm has been confirmed in tremolite, amosite and anthophyllite, and these defects have been shown to correspond to intercalation of lamellae of triple-chain structure parallel to (010). In anthophyllite these lamellae are observed to segregate into domains.

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The choice of axes in the amphiboles

Cited by 10 publications

References 5 publications

EXCALIBR to EXCELIBR and the Optical Orientation of Minerals: Correcting the Optical Orientation of Clinoamphiboles

EXCALIBR to EXCELIBR and the Optical Orientation of Minerals: Correcting the Optical Orientation of Clinoamphiboles

Genetics of Esterases in Man

High-resolution electron microscopy and diffraction studies of fibrous amphiboles

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