Glossary of Terms
Describing two or more crystals that twin in a repeated pattern (e.g. "repeated twinning") as depicted in the figure below. Named after the mineral Rutile, which most frequently exhibits this form of twinning. If there are six repeated crystals (i.e. another three crystals are added to the figure below in the same pattern), the agglomerate forms a circular structure, known as a sixling.
Color-Shaded Illustration of a Rutile Twin. Each Color Represents an Individual Crystal.