Answer:
Hoofed frolicking.
Pregnant every time you see her, yet she never will give birth.
Not born, but from a Mother's body drawn. I hang until half of me is gone. I sleep in a cave until I grow old. Then valued for my hardened gold.
This thing runs but cannot walk, sometimes sings but never talks. Lacks arms, has hands; lacks a head but has a face.
I sleep by day, I fly by night. I have no feathers to aid my flight.
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?