These views show square end views of a
few small andalusite crystals in a slate from Mariposa County,
California. Just a hint of zoning, caused by carbonaceous inclusions,
can be seen in the crystals. When the zoning is well deveoped
and appears as a cross it is termed chiastolite. The field
of view is about 2.5 mm.
These views show a twinned
andalusite crystal, partially altered to sericite.
Andalusite that shows a cross in end view is termed chiastolite.
The cross appears, in part, because of dark included organic
matter. The field of view is about 3.5 mm.