Here's a great specimen of one of the rarer forms of apatite - HYDROXYL-APATITE, from the #1 Shaft, 90' Level, Palermo Mine, North Groton, New Hampshire. The crystals form in "strings" which are actually stacks of sharp 6-sided individuals. I acquired this specimen in a trade with well-known New England collector Dana Jewel years ago, and he collected it himself in the late 1980s.