How is gold formed in rock?

Answer 1

Gold is not "formed" in rock so much as it will tend to concentrate under certain geologic conditions. We see evidence of gold grains in some rivers, and nuggets in some rock formations. There are also veins of gold that are frequently associated with quartz in some rock strata. This native gold has a good amount of silver in with it. There are massive quantities of gold floating around in sea water, but on the atomic level, and, as such, are not recoverable. Remember that gold is an element, and it isn't "made" or "formed" in nature so much as it is a part of the "mix" of the things that make up the earth's structure. A link can be found below to the Wikipedia post on gold. Check it out and pay particular attention to the section on Occurance.

Answer 2

They are found in sedimentary rocks mostly in sediment deposits.