Beautiful and educational! Under proper conditions pure minerals will develop into a crystal form characteristic of that mineral. This collection includes specimens that exhibit crystal forms from the six crystallographic systems (unique arrangement of atoms in a crystal). Includes a study guide defining and explaining terminology of crystals. 15 crystal specimens. Sizes vary with specimens available; in a compartment tray. Grades 6-12. Information on how to place your order by fax or by telephone. Product Number AM2305