I bought this from a lovely neighbor across the street from Michael dell in Austin and have had it many years. Dont know much except what I parroted from the COA.
Just taking a stab at the price... Things like Bolivia dry land treasure, Full cross, etc.
The item "90% Silver 8 Reales Spanish Coin Eight Real Potosi C1625 Colonial Cob wCOA" is in sale since Saturday, November 24, 2018. This item is in the category "Coins & Paper Money\Coins\ World\South America\Bolivia". The seller is "trufflers" and is located in Fort Collins, Colorado. This item can be shipped to United States.