When present in sulfide ore bodies, the gold, although still elemental in form, is so finely disseminated that concentration by methods such as those applied to alluvial gold is impossible. Native gold is the most common mineral of gold, accounting for about 80 percent of the metal in the Earth’s crust.

What ores is gold found in?

This is why gold is often found with quartz. These are known as primary gold deposits and to extract the gold the rock containing the veins of gold has to be dug up (mined), crushed and processed. Alluvial gold.

How many types of gold ore are there?

Based on the mineralogical characteristics and mineral processing techniques required, gold ores can be classified into 11 types (Table 1).

What kind of gold is there in the world?

Massive, base metal arsenical gold ores are rare, and there are only a few deposits in the world. A typical arsenical gold ore contains arsenopyrite as the major arsenic mineral. However, some arsenical gold ores, such as those from Nevada in the USA (Getchel deposit), contain realgar and orpiment as the major arsenic-bearing minerals.

Where is the gold found in gold ore?

In most gold ore, the gold is present in tiny specs, either within minerals like pyrite, or spread out free among the quartz. Normally even good, rich gold ore has no gold metal which is visible to the naked eye. The photo at left shows small particles of metallic gold in quartz taken from the mountains of Canada.

What kind of ores do you need to roast gold?

Straight pyritic ores, where the pyrite is present in small quantities, usually yield their gold to fine grinding and cyanidation alone. Silver ores containing the values as polybasite, stephanite, pyrargyrite (the antimony sulphide), and proustite (arsenic sulphide) usually require roasting.

How much gold is in a ton of ore?

It can vary from several thousand ounces to the ton down to a more typical .75 ounces per ton. It is all a matter of where the deposit is and how it was formed. According to the World Gold Council, larger and better-quality underground mines contain around 8 to 10g/t gold, while marginal underground mines average around 4 to 6 g/t gold.