Answer:
I am a precious stone, as clear as a diamond. Though you can walk on water with my power, try to keep me, and I'll vanish in an hour. What am I?
My first is in some but not in all. My second is in tiny but not in tall. My third in little but no in big. My fourth in port but not in pig. My whole is made in nature's way. For clothing rugs used every day.
I fly when I'm on and float coming off.
I shift around though always slowly. I never move more than a few inches at a time. A large movement by me can kill many people. I am huge yet unseen by humans.
Find me on body builders or in the drink aisle. What am I?
Two brothers we are, great burdens we bear. All day we are bitterly pressed. Yet this I will say, we are full all the day, and empty when go to rest.