they are Disk out of Hard Drive's,,, i take computers apart that dont work anymore and try to sell the gold,silver,platinum,, and other earth metals that they are made of this gold platters are what is in a computer hard drive 1980 to 1993 most like would be gold the newer hard drive platters are made with plated platinum and glass,, some still use aluminum as a base,,, old school like this are gold and aluminum and are best with aluminum cuz you can use nitric acid to eat the aluminum and other metal's from the gold.....
if someone dose it right that can get like 15 to 20 grams of gold from this disc or more,, if I had the money to do it I would but I don't so i'm just going to try to get some C's out of them if I can I do have more computer part like gold finger's and some old school processors for gold as well I'll be putting them on at a later time after I see if this will get me some more C's...