Occurrences of boron-free and boron-poor kornerupine

Friend, C. R. L.

doi:10.1180/minmag.1995.59.394.17

Cited by 2 publications

(5 citation statements)

References 11 publications

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“…This revision in the nomenclature has been approved by the Commission on New Minerals and Mineral Names of the International Mineralogical Association. In addition, we concur with Friend (1995) that the term boron-free komerupine sensu stricto be restricted to kornerupine analysed for boron and found not to contain it.…”

Section: Introductionsupporting

confidence: 88%

“…Friend, 1995). Many prismatine-bearing rocks are similar in being Mg-Al-rich and silica-undersaturated; indeed, both minerals have been found at one locality, or even in a single specimen in which B contents vary markedly.…”

Section: Comparison Of Prismatine and Kornerupine Sensu Strictomentioning

confidence: 98%

“…The difference in 73 composition between the type kornerupine sensu stricto (A1 < B < Si) and prismatine (B >> Si and A1) is sufficient to recognize prismatine and kornempine sensu stricto as distinct isostructural species. That is, 73 compositions (see structural formula above) are (B,Si,A1) in prismatine, (Si,B,A1) in borian kornerupine sensu stricto, and (Si,AI) in boron-free kornerupine sensu stricto (Klaska and Grew, 1991;Friend, 1995). For this reason, we re-introduce Sauer's (1886) name prismatine for a kornempine-structure mineral with B > 0.5 atoms per formula unit (p.f.u.)…”

Section: Rationale For Reviving the Name Prismatinementioning

confidence: 99%

“…Thus, use of the names kornerupine and prismatine would be analogous to the accepted use of the names spinel and hercynite for the group or Mg-dominant member and Fe-dominant member, respectively, of the MgAl2〇4 ~ FeAl2〇4 series, except that we make a clearer distinction between kornerupine sensu stricto and sensu lato. The modifier 'boron-free' should be applied only to kornenipine sensu stricto with B = 0 (Friend, 1995), and the modifier 'boron-poor' is a reasonable term for kornerupine sensu stricto with B < 0.2, a usage also recommended by Friend (1995). Strictly speaking, the distinction should be B > (Si + Al) (prismatine) and Si > (B + Al) (kornerupine sensu stricto).…”

Section: Rationale For Reviving the Name Prismatinementioning

confidence: 99%

“…is found in Mg-Al-rich, silica-undersaturated rocks m etam orphosed under upper am phibolite or granulite-facies conditions, of which the sapphirinekornerupine sensu stricto rocks associated with the Fiskenaesset Complex are a prime example (e.g. Friend, 1995). Many prismatine-bearing rocks are similar in being Mg-Al-rich and silica-undersatu rated; indeed, both minerals have been found at one locality, or even in a single specimen in which B contents vary markedly.…”

Section: Boron Per 215mentioning

confidence: 99%

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Prismatine: revalidation for boron-rich compositions in the kornerupine group

Cooper¹,

Hawthorne²

1996

Mineral. mag.

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Kornerupine and prismatine were introduced independently by Lorenzen in 1884 (but published in 1886 and 1893) and by Sauer in 1886, respectively. Ussing (1889) showed that the two minerals were sufficiently close crystallographically and chemically to be regarded as one species. However, recent analyses of boron using the ion microprobe and crystal structure refinement, indicate that the boron content of one tetrahedral site in kornerupine ranges from 0 to 1. Kornerupine and prismatine, from their respective type localities of Fisken~esset, Greenland and Waldheim, Germany, are distinct minerals, members of an isomorphic series differing in boron content. For this reason, we re-introduce Sauer's name prismatine for kornerupines with B > 0.5 atoms per formula unit (p.f.u.) of 22(O,OH,F), and restrict the name kornerupine sensu stricto to kornerupines with B < 0.5 p.f.u. Kornerupine sensu lato is an appropriate group name for kornerupine of unknown boron content. Kornerupine sensu stricto and prismatine from the type localities differ also in Fe2+/Mg ratio, Si -(Mg + Fe 2 § + Mn) content, A1 content, F content, colour, density, cell parameters, and paragenesis. Both minerals formed under granulite-facies conditions with sapphirine and phlogopite, but kornerupine sensu stricto is associated with anorthite and hornblende or gedrite, whereas prismatine is found with oligoclase (An9-13), sillimanite, garnet, and/or tourmaline. Occurrences at other localities suggest that increasing boron content extends the stability range of prismatine relative to that of kornerupine sensu stricto.

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Section: Introductionsupporting

confidence: 88%

Section: Comparison Of Prismatine and Kornerupine Sensu Strictomentioning

confidence: 98%

Section: Rationale For Reviving the Name Prismatinementioning

confidence: 99%

Section: Rationale For Reviving the Name Prismatinementioning

confidence: 99%

Section: Boron Per 215mentioning

confidence: 99%

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