The forms of apatite are many, diverse and colourful. Apatites are bred in the bone and borne out in the teeth, but domestic apatites are pale reflexes of the wild and exotic apatites you may find. In the many apatites of the world is much deception: you may think you have and hold one thing, but it is quite another. Look closely; you may see palaces and caves, heavenly clouds and hellish nightmare realms. But one thing is true: apatites are hard. Specifically, apatite is the defining mineral for 5 on the Mohs scale.
Yes, I’m spelling that right, and what is the Mohs scale? It’s the standard scale for hardness in minerals and other things. Talc is 1 and diamond is 10. So, strictly, apatite is exactly halfway up. But consider your teeth and bones: do they seem hard to you? One kind of apatite, hydroxyapatite, is the major component in tooth enamel and bone mineral.
Yes, apatite is a mineral. It’s actually a group of phosphate minerals. Its name, which sounds exactly like appetite, comes from Greek ἀπάτη apaté ‘deceit’; Abraham Gottlob Werner gave it the name in 1786 because apatite was often mistaken for other things. (To satisfy your appetite for etymology: appetite comes from Latin appetitus ‘desire’, from appetere, from ad ‘to’ plus petere ‘seek’.)
Minerals are fascinating things. Everyone should, in their childhood, spend some time in the minerals section of a museum. Try to go to one where they light them nicely. The mineral is mainly just arrangements of molecules made of calcium, phosphorus, oxygen, and either hydrogen (and more oxygen), fluorine, or chlorine – Ca10(PO4)6(OH,F,Cl)2. But take a look at how that all comes out. So many colours and shapes.
From such basic elements are our apatites built and crystallized, and yet they crystallize in so many different ways. Some are lucid, some opaque. Read into them what you will; see fantasy realms and dramas, or pure forms. Seek what you desire, but be prepared for deceit. There is no need to be uptight about it. In the end, know this: ordinary as they may seem to you, you have your own apatites, and you would be an indistinct useless mass without them.