I love panama medio balboas. I found 2 90% silver ones and 3 40%ers. I also found a few clad ones by accident because I only did edge search. "Accident" meant that I tilted the coins in my palm or I dropped the coins on floor, table, and the bag.
1966-72 were made of 40% silver and they used the same planket as our 40% JFK halves.
1930-62 were made of 90% silver.