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Albite twinning is very frequent, but in these rocks it is often accompanied by pericline twinning by which the broad or narrow albite plates are cut transversely by many thin, bright and dark bars as seen in polarized light.

The flowers, as before hinted, are thistle-shaped; the pericline or knob just under the florets is cone-shaped, covered with evenly set and pointed scales, green, edged with a brown margin, set round with short bristle-like teeth.