Nitric acid is the inorganic compound with the formula HNO3. It is a highly corrosive mineral acid. The compound is colorless, but samples tend to acquire a yellow cast over time due to decomposition into oxides of nitrogen. Nitric acid is also commonly used as a strong oxidizing agent.


  • Nitric acid is effective for detecting the presence of copper in an alloy.
  • A hard cupric reaction indicates lots of copper.
  • Mild cupric reaction indicates that at best the item is low karat gold (10K or below)
  • No cupric reaction does not indicate that the item is gold, just that there little or no copper.
  • Test the core of the item, not just the surface.
  • Nitric acid gold testing is a way to narrow down the possibility of an item being gold or not.


Appearance : Colorless liquid
Melting point :  −42 °C
Boiling point : 83 °C
Density : 1.51 g/cm3
Solubility in Water :  Miscible