This may seem kinda dumb, but I got a 1900 Morgan from a friend and I was trying to estimate it's value in my coin value book, and it says that the mint mark is on the reverse side under the eagle. I looked and looked, even got a magnifying glass and looked with that, but still couldn't find one. I know that some of the Philadelphia mint coins don't have mint marks, does this mean that this coin was minted there?