Apatite is one of a phosphate group of minerals. The colour can be blue, green, yellow or orange, so it can be confused with other gemstones.
Metaphysically this stone possess a deep spiritual knowingness which restores perspective on what is really important in life. Meditation, Spiritual Guidance, most importantly a deep sense of fulfillment. Despite that it's also a very grounding stone which inspires you to reach out and achieve things. Certainly it eases conflicts between the spiritual and material worlds.