If you took all of the gold in the world and put it in one place, how much woul  

I think more than a mountain.
Economic gold extraction can be achieved from ore grades as little as 0.5 g/1000 kg (0.5 ppm) on average in large easily mined deposits. Typical ore grades in open-pit mines are 1–5 g/1000 kg (1-5 ppm), ore grades in underground or hard rock mines are usually at least 3 g/1000 kg (3 ppm) on average. Since ore grades of 30 g/1000 kg (30 ppm) are usually needed before gold is visible to the naked eye, in most gold mines the gold is invisible.

Since the 1880s, South Africa has been the source for a large proportion of the world’s gold supply. Production in 1970 accounted for 79% of the world supply, producing about 1,000 tonnes. However, production in 2004 was 342 tonnes. This decline was due to the increasing difficulty of extraction and changing economic factors affecting the industry in South Africa.

The city of Johannesburg was built atop the world's greatest gold finds. Gold fields in the Free State and Gauteng provinces are deep and require the world's deepest mines. The Second Boer War of 1899–1901 between the British Empire and the Afrikaner Boers was at least partly over the rights of miners and possession of the gold wealth in South Africa.
Gold nuggets From Arizona
Gold nuggets From Arizona

Other major producers are Canada, United States and Australia. Mines in South Dakota and Nevada supply two-thirds of gold used in the United States. Siberian regions of Russia also used to be significant in the global gold mining industry. Kolar Gold Fields in India is another example of a city being built on the greatest gold deposits in India. In South America, the controversial project Pascua Lama aims at exploitation of rich fields in the high mountains of Atacama Desert, at the border between Chile and Argentina. Today about one-quarter of the world gold output is estimated to originate from artisanal or small scale mining.

t is amazing, but the total amount of gold in the world is a surprisingly small quantity. If you look it up in an encyclopedia, you will find that the annual worldwide production of gold is something like 50 million troy ounces per year. Gold has a specific gravity of 19.3, meaning that it is 19.3 times heavier than water. So gold weighs 19.3 kilograms per liter. A liter is a cube that measures 10 centimeters on a side. There are 32.15 troy ounces in a kilogram. Therefore, the world produces a cube of gold that is about 4.3 meters on each side every year. In other words, all of the gold produced worldwide in one year could just about fit in the average person's living room!