I was given an unopened, uncirculated bag from the U.S. Assay Office San Francisco containing $50 worth of 1970 pennies. Is it of more value sealed as it is, or opened?

Sealed

I believe you knew the answer to your question...i mean come on.

I would leave it sealed unless you are looking for something in pertecular

Usually more valuable sealed.

Being myself, if I was to sell the bag with Coins, I would leave it sealed. If I am looking for certain 1970's pennies, I would open the bag, search and sell what you don't want.