Enthalpy of diaplectic labradorite glass

K. L. Geisinger, A. Navrotsky, J. Arndt

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2 Scopus citations


Enthalpies of solution in molten 2PbO·B2O3 at ∼988 K have been measured for diaplectic labradorite glass from the Manicouagan impact crater and a fused glass formed from the same material. The enthalpies of solution of the diaplectic and fusion-formed glasses are 4,347 and 2,023 cal mol-1, respectively. The more endothermic enthalpy of solution of the diaplectic glass indicates a greater relative energetic stability of about 2.3 kcal mol-1. The data are consistent with Diemann and Arndt's (1984) structural model that suggests the diaplectic glass is more ordered than fusion-formed glass and with the presence of crystallites. Comparison of data to enthalpies of solution of crystalline labradorite (Carpenter et al. 1985) indicates a maximum percentage of crystalline relics of ∼15-18%, also consistent with Diemann and Arndt's (1984) estimate of <17%. Thus the diaplectic glass is intermediate in thermochemical properties between normal glass and crystal (much closer to glass) and does not represent any state more unstable than normal fusion-formed glass.

Original languageEnglish (US)
Pages (from-to)357-359
Number of pages3
JournalPhysics and Chemistry of Minerals
Issue number6
StatePublished - Nov 1986
Externally publishedYes

ASJC Scopus subject areas

  • General Materials Science
  • Geochemistry and Petrology


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