I have one... yet, I can not catalog it, From coinsandhistory.com:
By secret decree of Marshal Andrés de Santa Cruz, strong man of Bolivia, minor denomination coins were to be struck in low grade (.6666 fine) silver. This did not affect the larger 8 Soles which were made for export to Europe but all coins from 4 Soles and less were made with the debased silver.
Additionally the design and the date of the coins was to be frozen with the year "1830". Production of these debased silver coins continued until a new design appeared in Potasi in 1853.
It appears like the 4s, except for the denomination...