Thursday, July 11, 2013

Is it Gold?: the Basic Acid Test

(Is it gold, pyrite, or?)

It's not unusual for me to get e-mail requests to identify possible gold ores and unusual material or unidentified grains that remain as part of gold mining concentrates. I usually do my best to help, but there's a very reliable way to tell whether what you hold in your hot little hand is gold or not.

What might that be, you ask? A simple acid test (and the one I'm about to describe is not the only one, by the way).

Lest I lure you into a false sense of security, let me me tell you here and now that the process I'm about to describe is potentially harmful if you're not wearing the right personal protective gear or can't seem to take things slowly and carefully. I tend to be an impatient type, but when running an acid test you best not follow in my footsteps in that regard.

Cautionary Note: I'm writing this post as an informational piece only. I take no responsibility if things go awry. Moreover, I highly recommend you avoid the following approach and purchase a premixed chemical gold test kit instead. They are much safer to use and come with step-by-step instructions.

Gold Concentrates
Gold Pans
Gold Concentrators
OK, here's what you'll need to test for gold:
  • Chemical face shield or safety goggles (the type that cover the side of your eyes, not just the front).
  • Thick rubber chemical gloves. These typically go up to nearly mid arm in most instances and are lined. 
  • A rubber lab apron, lab coat, or heavy overalls (or similar protective outerwear).
  • Two glass test tubes or vials (I don't recommend using plastic or Nalgene tubes or vials).
  • A small glass lab funnel.
  • Bottles of hydrochloric acid and sulfuric acid (alternately, you can purchase a gold chemical test kit where both these acids are already mixed into one solution).
1) OK, if you want to test for gold the old school way get yourself suited up in your protective gear.

2) Find a well-ventilated location in your garage or shed, or just set up on a bench or table outside where any spills or splashes won't cause havoc with your spouse.

3) Use a small glass lab funnel and very slowly fill your test tube or vial halfway with either sulfuric or hydrochloric acid.

4) Once again, very slowly pour an equal amount of the other acid into the vial or test tube (i.e., sulfuric into hydrochloric or hydrochloric into sulfuric).

IMPORTANT NOTE: Chemically speaking, there is not supposed to be a chemical reaction when mixing sulfuric acid with hydrochloric. The mixture becomes an aqueous solution that is weaker or stronger depending on how much of one acid is mixed with the other. Regardless, handling acids like these is not something to be taken lightly, especially if a person is not wearing proper protective gear. Both acids can cause potentially severe damage to human tissue like the skin, your eyes, and via inhalation

5) Next, take a small piece of what you think might be gold (or one of those suspect grains left in your concentrates) and drop it into the mixture vial.

6) If the material you dropped into the vial or test tube dissolves, IT ISN'T GOLD (sometimes dissolution happens immediately and at other times you may have to wait a few minutes).

7) If even the slightest portion of the suspect material you dropped into the mixture vial or test tube remains, then voila! IT'S GOLD.

I'm no chemist but an engineering type, so I'm sure some chem lab worker or PhD out there is gonna hit me on the fine points here. However, all you need to know is that this simple acid test will work in the greatest majority of cases.

Dr. Frankenstein, I Presume?

Additionally, some of you are going to pooh-pooh all my safety concerns but I work at a well-known national laboratory and if I were to do anything (and I mean anything) without the proper protective gear, my skinny ass would be in the unemployment line the following day. Better safe than sorry, anyway...right?

Once again, here's a suggestion from an old timer? Shell out a few bucks and buy yourself a premixed gold acid test kit online. These are even sold on eBay. That way you don't have to go through all of these steps or create greater risk...unless you have a bit of Dr. Frankenstein in you and you love playing with chemicals and test tubes.

At any rate, what's described above has been around for quite a while and forms the basis for one type of fundamental chemical assay. By the way, did I hear someone mention the term aqua regia out there? If so, we'll talk about that form of chemical "reverse engineering" regarding testing for gold at a later date.

Be safe out there.

(c)  Jim Rocha (J.R.)  2013

Questions? E-mail me at


  1. There has been many times I could have used this. Now days though you would be labeled a terrorist of a meth cooker if you try to get chemicals of any kind. I got the "eye" for buying bleach the other day. I was told 50/50 mix of bleach and water kills weeds..... JR, I don't like what this country is turning into, and I don't know how to fix it........The land of the free is dead I'm afraid....

  2. Well I don't think we're dead Gary, but the course surely has to be changed. Best, J.R.

  3. So is that in the picture gold or not? We never got the answer.Nice article though. Thanks for the information.

  4. That's gold my friend. Best, J.R.