Mistakes happen. Do you have something to say about this coin? I figure someone cracked it out of a proof set.
Where would San Francisco have gotten a 90% silver planchet in 1968? Theyhadn't had silver quarter sized planchets since 1954. They did strike some 90% silver coins for other countries in 1967 but the planchets were much larger and thicker. Even a quarter planchet accidentally cut from strip intended for those coins would have resulted in a coin well overweight. This would have to be another workman assisted "error".
