http://en.wikipedia.org/wiki/Ferrous_sulfate
When I make copperas ferrous sulfate it looks like the crystals in the wiki photo, copperas if crystals are dried completely and not stored wet and slightly acidic can oxidize easily, the oxidized iron (rust) will not precipitate gold, since you description sounds like you have some oxidation of your crystals, but for the most part good copperas, what I would try is to use a 10% H2SO4 solution to dissolve them, using heat, use minimum liquid needed to get them into solution, the heat can be pretty hot, once dissolved pour into a cooling jar, let it sit to settle out in-solubles, decant filtering solution, if you wish at this point to recrystallize, heat them and evaporate off water, do not dry out crystals completely, as crystals form and pile up on the bottom of the pot spoon them out put into small HDPE plastic bottle, add just a few drops of H2SO4 to maintain acidity,keep air from the crystals with a good lid, if you wish to store the filtered liquid add a few drops of HSO4 to keep solution slightly acid, store with lid to keep out air as much as possible.
There is not any reason to buy copperas,unless you just want to, you can most likely make a better product than you can buy most places, it is very easy to make at home, in an couple afternoon you can make a large batch to stock your supply to last a while, transformer laminates are fairly pure soft iron and work great for the iron needed, I cut or grind the welds on the transformer, pull out laminates and separate them, the copper coil can be sold or used for other projects (rewinding that heater fan motor on your truck, orthe very fine copper wire incenerated and used to start the cementing process of silver from the nitrate solution...), the iron laminate's are torched to burn off laquer coating, if you do not use then now store in plastic bag to keep them from rusting.
Wash the laminate iron off cut to small pieces with tin snips, in your ceramic casserole dish on your hot plate add 10% H2SO4 solution dissolve the laminates, once dissolved pour into a cooling jar, let it sit to settle out in-solubles, decant filtering solution, if you wish at this point to recrystallize, heat them and evaporate off water, do not dry out crystals completely, as crystals form and pile up on the bottom of the pot spoon them out put into small HDPE plastic bottle, add just a few drops of H2SO4 to maintain acidity,keep air from the crystals with a good lid, if you wish to store the filtered liquid add a few drops of HSO4 to keep solution slightly acid, store with lid to keep out air as much as possible.
