Back in the early 80's, whem precious metals like Gold, Platinum, etc. were sky high in price, I used to make extra money recycling catalytic converters. Back then they only used Platinum, and it was found in two forms: one was the honey comb used by Ford and Chrysler, the other were ceramic beads or pellets, used by GM and American Motors. One converter held either 6 lbs. of beads, or 2 lbs. of honey comb. Just to give you and idea of how little catalyst was actually in each one, I was paid approx. $4.00 a lb. for the Honeycombs, and $2.00 lb. for the beads. Part of the reason they now use Palladium, Rhodium, etc. is that Platinum went way up in price, and there were also concerns about its availability from South Africa and the other main source, the (then) Sovet Union...