Question about copperas

[leavemealone]

I purchased a large bag (4lbs) of a product today simply called Copperas.Its made by the company Hi-Yield.The contents on the back are 11%combine sulfur and 19%water soluble iron.Now did I get the correct thing?I had about 800ml of a mixture of nitric and muratic and had a little gold in it.It is pretty much my disposal bottle.I throw little bits of used acid in it and deal with it when Im done.Well I mixed up some of the copperas with water and a little clean muratic,and poured just a little in the bottle.The entire solution turned jet black instantly and then went back to clear green after I agitated it a minute.I know why the solution did what it did,I do not need any help or comments about that,I just want to know if this sounds like I purchased the correct product.Does this sound like the copperas I need to be using for droppong gold?If the general consensus is no then I will purchase what I found online.
Thanks

 

[butcher]

should be ok ,if green, not oxidized brown.

 

[leavemealone]

Yes it is green......its light green but still green.I wish I had my camera here,I could post a couple of pics just to make sure.But it is definitley not brown.

 

[butcher]

they also use a small crystal of ferrous sulfate (copperas) to test for gold, very similar to the stannous chloride test. for fun try a drop of known gold solution on a crystal of your copperas.