Jesus said that it's harder for a camel to squeeze through the eye of a needle than for a rich man to enter the Kingdom.It would make sense, then, that the first mention of gold in Genesis describes it outside the garden, out where the rivers are separated.
A river watering the garden flowed from Eden; from there it was separated into four headwaters. The name of the first is the Pishon; it winds through the entire land of Havilah, where there is gold.
Genesis 2:10-11 (NIV)
"But Josh, there's gold in the New Heaven and new Earth. It's in the Revelation!"
Yes. I know. And Jesus said "with God, all things are possible" in the same story. And gold will likely have a different meaning in a world where there is no scarcity. Just like in Eden.