Hello, first post for me. I have been reading a lot and have started refining some scrap gold alloy we use in our Mfg. The alloy is 71% Au, 4.5% Ag, 8.5% Pt and the balance is Copper. I have dissolved about 238 Gms of this alloy in AR and I have a very fine black powder in this solution. It does not filter out in a coffee filter. The silver chloride was retained however. The alloy specification has a trace amount of Iridium and Palladium ( each less than .005%). I do not want to proceed further without some advice?