Why gold nuggets are found in quartz veins?

Why in the News?

Researchers have been curious about why the majority of gold nuggets discovered throughout history have been found in orogenic quartz veins.

Location and distribution of Gold:

• Orogenic gold systems are commonly found in mountainous regions where large-scale geological processes, such as the collision of tectonic plates, have occurred.
• For example, the Himalayas, the Canadian Shield, and the Western Australian goldfields.
• Large gold nuggets are often found in orogenic quartz veins formed during the tectonic processes that create mountains.
• These nuggets form because, during earthquakes, the stress on quartz crystals causes a reaction that deposits gold on their surfaces. This process happens repeatedly, leading to the accumulation of gold nuggets.

Findings by Researchers:

• • Piezocatalytic Effect and Gold Accumulation: Researchers discovered that the piezocatalytic effect of quartz under seismic stress causes the accumulation of gold in quartz veins.
    • The piezoelectric quartz crystal generates an electric field when subjected to stress. 
    • This field can drive electrochemical reactions at the interface between the quartz and a surrounding aqueous solution containing dissolved gold. These reactions cause gold to be deposited on the quartz surface. 
  • Seismic Activity and Localized Gold Deposits: The study suggests that gold nuggets in orogenic systems are formed through repeated piezocatalytic reactions over time, driven by natural seismic activity. This process explains the highly localized and interconnected nature of gold deposits within quartz veins.
  Conclusion: Researchers have found that gold nuggets in orogenic quartz veins form through piezocatalytic reactions caused by seismic stress on quartz. This process drives gold deposition on quartz surfaces, explaining the concentration and localization of gold in mountainous regions.

Mains PYQ:

Q Craze for gold in Indian has led to surge in import of gold in recent years and put pressure on balance of payments and external value of rupee. In view of this, examine the merits of Gold Monetization scheme. (UPSC IAS/2015)