Abstract
Relative compressibilities of five silicate garnets were determined by single-crystal x-ray diffraction on crystals grouped in the same high-pressure mount. The specimens include a natural pyrope [(Mg2.84Fe0.10Ca0,06) Al2Si3O12], and four synthetic specimens with octahedrally-coordinated silicon: majorite [Mg3(MgSi)Si3O12], calcium-bearing majorite [(Ca0.49Mg2.51)(MgSi)Si3012], sodium majorite [(Na1.88Mgp0.12)(Mg0.06Si1.94)Si3O12], and an intermediate composition [(Na0.37Mg2.48)(Mg0.13Al1.07 Si080) Si3O12]. Small differences in the compressibilities of these crystals are revealed because they are subjected simultaneously to the same pressure. Bulk-moduli of the garnets range from 164.8 ± 2.3 GPa for calcium majorite to 191.5 ± 2.5 GPa for sodium majorite, assuming K′=4. Two factors, molar volume and octahedral cation valence, appear to control garnet compression.
Original language | English (US) |
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Pages (from-to) | 344-349 |
Number of pages | 6 |
Journal | Physics and Chemistry of Minerals |
Volume | 21 |
Issue number | 5 |
DOIs | |
State | Published - Sep 1994 |
ASJC Scopus subject areas
- General Materials Science
- Geochemistry and Petrology