metacrystn.
/ˈmɛtəkrɪst/, U.S. /ˈmɛdəˌkrɪst/ Geology.
A large crystal formed in a metamorphic rock by recrystallization, surrounded by a finer-grained groundmass of other metamorphic crystals; a porphyroblast.
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the world > matter > chemistry > crystallography (general) > crystal (general) > crystal types > [noun] > specifically by method of crystallization
xenocryst1894
metacryst1913
porphyroblast1920
1913 W. Lindgren Mineral Deposits xi. 158 An individual in another may be briefly called a metasome; if the metasome develops strongly with crystal outlines it may be called a metacryst.
1932 F. F. Grout Petrogr. & Petrol. 365 Metacrysts commonly have abundant inclusions..and in some the inclusions are oriented so as to show that the metacrysts grew by replacement.
1963 D. W. Humphries & E. E. Humphries tr. H. Termier & G. Termier Erosion & Sedimentation xvii. 339 Dolomite is present in limestones as rhombic ‘metacrysts’ which can cut across original structures (for example, oolites) and fossils.
1988 Internat. Geol. Rev. 30 1070/1 Metacrysts form as a result of metasomatic processes of mineral formation during the replacement of the mono- or polymineralic precursor by crystalline individuals..of different chemical composition.
This entry has been updated (OED Third Edition, December 2001; most recently modified version published online March 2022).
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n.1913