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Scientists Unravel the Reason Behind Arsenic Presence in Gold Deposits

  • Uncategorized
  • Sep 16, 2021

Gold is considered to be one of the most precious metals on this planet. Till now, scientists have not been able to justify why gold deposits or concentrations are found as it is one of the most inert metals on the periodic table, which means it does not react easily with other metals and substances. Now an international group of geochemists has successfully discovered the concentration of gold alongside arsenic which leads to the formation of most gold deposits. This also explains why many of the gold miners have been at risk from arsenic poisoning.  

Gold is valued for its purity and stability, and it is rare enough to retain its value: The World Gold Council estimates that all gold ever mined in the world can fit into a 20 x 20 x 20-meter cube. In nature, some gold exists in the form of gold nuggets, but a significant amount is bound up with minerals such as pyrite and arsenopyrite, which are iron-arsenic-containing minerals. These minerals act like sponges for gold and are capable of concentrating up to 1 million times more gold than other parts of nature (such as gold-containing hot springs). This gold is invisible to the naked eye as it is chemically bound with minerals.

 A team of scientists used an intense X-ray beam produced by the European Synchrotron (ESRF) in Grenoble, France, to study the effects of concentrated gold minerals, which can test the chemical bonds between minerals and gold. They found that when the mineral is enriched with arsenic, gold can enter mineral structural sites by directly binding to arsenic (forming, chemically speaking, Au(2+) and As(1-) bonds), which allows gold to be stabilized in the mineral. However, gold only forms weak gold-sulfur bonds with the mineral when the arsenic concentration is low as gold doesn't enter the mineral structure.