Barrick Gold (ABX:US), the world's largest gold producing company having reserves of more than 140 million ounces of gold in it's mines all over the world fell to a two decade low recently due to crash in gold prices and some of it's own internal problems.
The average cost of production of 1 ounce of gold at barrick gold is around $950 USD and was selling it at more than 100% premium when the gold price touched $1900 per ounce in 2011. Consequently the stock touched an all time high of $56 on 21st April 2011 and was having a huge market value of around $56 billion then. The stock is now hovering around $15 with a market value of $15.5 billion.
The average cost of production of 1 ounce of gold for large gold miners are in the range of $1000 - $1100 range and the gold price is currently hovering around $1200. Considering the cost of production, a significant and durable fall below $1100 per ounce seems unlikely.
Even at $1100 of gold price the gold reserves of Barrik gold is valued at more than $150 billion which makes the stock quite attractive if it falls below $14.