see excerpt from market cap, outlining porphyry can be economic...

see excerpt from market cap, outlining porphyry can be economic on very low grades

”It is often difficult for investors to assess the potential economic value of exploration results. In particular, the low grades that are characteristic of large, disseminated, copper-gold systems.These systems are typically Porphyry-style deposits, but can also be of Iron Ore Copper Gold or Replacement style.
The point is that large, disseminated, copper-gold systems can be profitable at very low grades. The investor therefore needs to know the style of mineralisation and the potential size of the deposit in addition to grades. Conversely, narrow, discontinuous, but high grade deposits may require a very high cut-off grade to be economically mined.See excerpt from market cap.

In 2012 the Paracatu mine, operated by Kinross Gold Corporation in Brazil, treated around 58 million tonnes of ore at a grade of around 0.4grams per tonne (“g/t”) to produce 466,709 ounces of gold. At December 2012 it had reserves of 1.4 billion tonnes at grade of 0.40g/t gold for a total of 18 million ounces of gold. The cut-off grade is around 0.2g/t gold.”