Answer:
Late afternoons I often bathe. I'll soak in water piping hot. My essence goes through. My see through clothes. Used up am I - I've gone to pot.
I am partially baked. I am not completely lit. I am a portion of the moon. I am lesser than full wit. I am a divider of the hour. I am not a total lie. I am a sibling through one parent.
I am needed for most animals and hardcover books
I am the minerals vital for your good health.
At night I come without being fetched, and by day I am lost without being stolen. What am I?
No matter how little or how much you use me, you change me every month.