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1) you can do from general knowledge
or see http://en.wikipedia.org/wiki/Gold
2) is an interesting question as you need to define the property, before you can state a difference. For example gold is very much more dense than 'ordinary' rock (what ever that is), so there is a big difference. Both 'ordinary' rock and gold are found naturally in the ground, so there is no difference in the source.
3) see http://www.thefreedictionary.com/goldmine
GOLD DUST FOR SALE
Dear Sir/ Madam,
We are small scale Gold miners here on the sub-region of West Africa. We have some huge
quantity of alluvial Gold Dust for sale at a considerable price of $30,500USD per kilo
which is below world market price, 22 carat and 92.05% purity. If you are interested, do
not hesitate to get back to us as soon as possible for us to give you our full co-operate
MR BENSON IMO