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Twinning by metric merohedry

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    19628

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    Twinning by metric merohedry is a special case of twinning by merohedry which occurs when:

    • the lattice of the individual has accidentally a specialized metric which corresponds to a higher holohedry
    • the twin operation belongs to this higher holohedry only

    If H is the individual point group, D(H) the corresponding holohedry and D(L) the point group of the lattice, twinning by metric merohedry corresponds to D(L) ⊃ D(H) ⊇ H

    Twinning by metric merohedry can be seen as the degeneration of twinning by reticular merohedry to twin index 1, or of twinning by pseudomerohedry to twin obliquity zero.

    Twinning by metric merohedry is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Online Dictionary of Crystallography.