This is largely a hydroxylapatite specimen. There are two phases, the darker, solid hydroxylapatite on the left and the lighter, more porous hydroxylapatite on the right. The lighter phase has a number of cavities in it that are lined with gemmy, sharp hydroxylapatite crystals. Some of the cavities are filled with alphaltic bitumen on the apatites. There is thin 2-3mm thick phase of platy collinsite between the light and dark. Very interesting specimen!
