Gold acts like a sponge and absorbs nitric acid. This enables the nitric acid to clean the gold, such as gold nuggets or free gold taken from black sands. Most gold found in nature contains other metals, but some of these cannot be taken down in nitric acid (such as the platinum family).
First; The Dangers of Nitric Acid
- Place gold in a beaker or Pyrex container.
- Mix 3 parts distilled water or spring water to 1 part nitric acid in the beaker or Pyrex container that contains the gold.
- Place on stove or hot plate until only the gold is showing. 4
- Add a very small amount of nitric acid to check if all the metals, except the gold, are in solution. If the acid does not bubble around the gold, then the metals are in solution. 5
- Add 10 parts tap water.
- Filter the gold out of the container through a plastic strainer or funnel lined with a filter. The gold will be clean and pure.
- Let the filter and gold dry and put them into a crucible.
- Light the filter with a match and burn it.
- Cover the burned filter and gold with borax.
- Put the crucible in a furnace or oven. Fire the gold at 1950 degrees F. When the gold lays flat, looks like honey and has no lumps in it, it is ready.
- Quickly pour the gold into a mold and let it set in the crucible until it has cooled.
- Remove the gold and clean it with soap and water.
You should always check for silver when cleaning gold with nitric acid, Drop a small amount of un-iodized table salt into the nitric acid and water solution. Proceed with steps 6 through 14 of How To Use Nitric Acid To Purify Silver