The 50g Iron ore powder sample has 10% Fe, and little amounts of Cu, Zn, Pb, As, Mn, Ca, Ti, Sn, and other non-metal elements.

I have an machine to read X-ray spectrum and what I'm looking for are the precious metals (especially Gold).

To reduce the interference from other cheap metals (Fe, Cu, Zn, Pb, As), I used around 100cc HCl (unknown concentration) to dissolve the powder sample. The process was done in a chamber and heat was constantly provided.

The temperature throughout the process was unknown though..

Anyway, the process was done 'sort of' successfully, the Pb and As were completely removed and Fe was reduced to 5%. My question however is that..

During the process, at first the solution was forming bubbles, then while heat was constantly given, it started to give more bubbles and it looked like boiled water. After 15mins, the solution started to 'spit' and liquid droplets were 'fired' from the solution to the wall of the beaker. After 5 more minutes, I stopped providing heat and let the solution cool down.

I wonder, if I stopped too early.

Was the 'spitting' part indicating the HCl was actually undergoing reactions with my powder sample? Did I stop too early before the reactions could go fully done?

Edit 1: In addition, the whole process took about 30-40 mins.. Now it has 10% Ca and 5.6% Fe left. The X-ray machine only reads elements after Ca so it doesn't tell concentrations of H, C, O, Na.. So I can only guess the leftover Fe is from some Fe compound(s) which HCl cannot dissolve..?

Edit 2: I still can't find Au spectrum peaks significantly but I've found one (Haha.. Yes. only one by far) needle-like yellow-wish orange-wish piece of metal through microscope. I hope that is Au. And what I'm asking is because I'm wondering to apply acid again or smelt it.. Maybe apply HCl one more time..? or this time I use H2SO4....? or simply put the powder into furnace......?

Edit 3: There're a lot of pink-purple-wish metal pieces when I scan the powder sample through microscope.. I wonder what they are........