I found out a little info on your flask..On pg. 483 in American Glass, there is a drawing of your flask. On the next page, it is written about as follows: circa 1860-1875..listed as pint, clear deep olive-green. Also occurs in quart. What a great find! If I can dig up more info, I'll post it.
hi kentohio
your flask could you post a better photo to show color if it is the dark olive green aka black glass it is a good one to get all though listed as common it is not common in that color colors come in emerald green and aquamarine and olive green lateley you could get possably 450$ or higher i know 1 sold in 1988 for 130$ and i am preety sure hecklers sold one for much more great find and great item have a good one
bob
I'll try to take a picture in a few days. There are some areas so thick and dark that sunlight won't shine through. Lower in the flask the glass is thinner and it looks dark olive with strong light behind it.