Why Dig Deep for Gold?
The gold mines are dug deep to
find traces of gold but a new research done by a researcher from the University
of Geneva (UNIGE) has found that gold deposits appear near to the surface while
copper deposits are seen at greater depths. The results of the study
published in Nature Communications is expected to help miners locate precious
and base metals better.It was also noted that 95% of gold deposits are lost to
the atmosphere through volcanic emissions.
Massimo Chiaradia, researcher in the Department of Earth Sciences in UNIGE noted deposits are formed due to geological processes. Some Porphyry type deposits are formed underneath volcanoes by an accumulation of magma that releases fluids on cooling and precipitates metals in the form of ore. The porphyry deposits are found mainly around the Pacific Ring of Fire, produce three-quarters of the natural copper and a quarter of the natural gold mined. A copper deposit may have 1 to 150 million tons while the quantity of gold may be 10 to 2500 tonnes.
Less than one percent gold is seen in deeper copper-rich deposits while in deposits located upto a depth of three kilometer it climbs to 5%. In view of the higher copper demand, miners need to understand that there are two porphyry deposits and how they are formed. In deep deposits, mineralisation of copper happens over a long period, while shallow deposits may contain more gold. In the deeper deposits, liquid and vapor form a single fluid phase, which precipitates the copper quickly and makes the gold leak into the atmosphere as the fluid rises to the surface.
It’s a valuable indication for the mineral exploration industry, which now knows at what depth it will find large deposits of copper, or conversely large gold deposits, irrespective of the volcano,” concludes Chiaradia.