Digger gold is the common slang term for gold

Gold

Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...

 recovered from electronics components such as board fingers, CPUs, and connector pins. For the gold fingers on boards or circuits

Electronic circuit

An electronic circuit is composed of individual electronic components, such as resistors, transistors, capacitors, inductors and diodes, connected by conductive wires or traces through which electric current can flow...

, often a stripping solution is used to remove the gold from the board material, nitric acid

Nitric acid

Nitric acid , also known as aqua fortis and spirit of nitre, is a highly corrosive and toxic strong acid.Colorless when pure, older samples tend to acquire a yellow cast due to the accumulation of oxides of nitrogen. If the solution contains more than 86% nitric acid, it is referred to as fuming...

 also works well in this regard as many gold components are soldered to boards with silver-based solders that are soluble in nitric acid (which gold is not). After dissolving all other metals in solution, the digger gold is recovered by dissolution of the gold in aqua regia

Aqua regia

Aqua regia or aqua regis is a highly corrosive mixture of acids, fuming yellow or red solution, also called nitro-hydrochloric acid. The mixture is formed by freshly mixing concentrated nitric acid and hydrochloric acid, usually in a volume ratio of 1:3, respectively...

 and subsequent selective precipitation

Precipitation (chemistry)

Precipitation is the formation of a solid in a solution or inside anothersolid during a chemical reaction or by diffusion in a solid. When the reaction occurs in a liquid, the solid formed is called the precipitate, or when compacted by a centrifuge, a pellet. The liquid remaining above the solid...

 of the gold using copperas or another selective reducing agent

Reducing agent

A reducing agent is the element or compound in a reduction-oxidation reaction that donates an electron to another species; however, since the reducer loses an electron we say it is "oxidized"...

 such as hydrazine

Hydrazine

Hydrazine is an inorganic compound with the formula N2H4. It is a colourless flammable liquid with an ammonia-like odor. Hydrazine is highly toxic and dangerously unstable unless handled in solution. Approximately 260,000 tons are manufactured annually...

. Due to the cost required and the small amount recovered, digger gold is not necessarily cost effective.

See also

• eDay
  EDay
  eDay is a term that refers to the peak sales day for the online retail sector in the United States. The term was coined by web analytics and precision marketing firm Coremetrics.-eDays by year:* December 5, 2005....
  
  
• The WEEE directive (Waste Electrical and Electronic Equipment)
• Computer recycling
  Computer recycling
  Computer recycling or electronic recycling is the recycling or reuse of computers or other electronics. It includes both finding another use for materials , and having systems dismantled in a manner that allows for the safe extraction of the constituent materials for reuse in other...
  
  
• E-Cycling