Testing for Gold with a Blowpipe Analysis

This shows several ways to use a blowpipe for mineral analysis.
Gold is the only metal that is yellow that is not affected by normal acids or other chemicals with a few exceptions a mixture of nitric and hydrochloric acids called aqua regia is one.  Gold is also soluble in a solution of sodium or potassium cyanide.  A simple test for gold can be made using a blowpipe analysis and some nitric acid.

Step 1. First grind a small sample of gold ore to a powder in an agate mortar.

Step 2. Mix this powder with an equal amount of either borax or sodium carbonate.

Step 3. Place this powder into a recess in a charcoal block.

Step 4. Blow a hot flame onto the sample with a blowpipe.

Step 5. After the sample has melted allow it to cool.  If gold is present it will collect as a small button at the base of the melted sample.

Step 6. Dissolve the sample in water saving the part that doesn’t dissolve.

Step 7. Put the residue into a small amount of dilute nitric acid, if it is yellow in color and doesn’t dissolve it is gold.


Do not get any acids on you!

Cyanide is deadly poisonous, don't eat the stuff!