12-Sided Snowflakes by Kenneth G. Libbrecht, Caltech: Sometimes capped columns form with a twist, a 30-degree twist to be specific.  The two end-plates are both six-branched crystals, but one is rotated 30 degrees relative to the other.  This is a form of crystal twinning, in which two crystals grow joined in a specific orientation. #Snowflake #12_Sided_Snowflake
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