Answer:
Your reflection can be seen here, as long as youβre not moving.
Sometimes it's silver but also gold. Printed on paper it's a treasure to hold. What is it?
Humans have two that shrink in the light and expand in the dark
If you have me, you want to tell me. If you tell me, you don't have me.
In many hallways you would stand, if not with this in hand.
Two little holes in the side of a hill. Just as you come to the cherry-red mill.