Roger Weller, geology instructor
firstname.lastname@example.org copyright 2010-R.Weller
Andalusite is (AlF)2SiO4
One variety of andalusite, chiastolite, forms as gray, block-like crystals that are so
rounded that you are not even sure that what you have is really a crystal. However,
when slices are made at right angles to the length of the crystal, these slices display
a dark cross or square pattern due to carbonaceous inclusions. To make matters
even more interesting, each slice in the same crystal will display a slightly different
Photo is copyright free only for non-commercial educational uses.
Just credit photo to R.Weller/Cochise College.