Answer:
A precious stone, as clear as diamond. Seek it out while the sun's near the horizon. Though you can walk on water with its power, try to keep it, and it'll vanish in an hour.
It is a path of cow juice spread across the sky but cannot be seen by the naked eye
The more you take, the more you leave behind.
What is bought by the yard by is worn by the foot?
My tongue hangs out as I run over fields and streets all day. I get tied up every morning and untied at night.
I am rarely touched but often held. If you are smart you'll use me well. What am I?