I've been contemplating the capital gains tax on Bitcoin.

The Bitcoin protocol is a trustless system; so Bitcoins exist in the blockchain as a stake of irrefutable ownership. It's been said, "If you don't own the private keys to the wallet containing Bitcoins, you don't own Bitcoins."

For capital gains tax, ownership is everything. When a coin is created it is certainly owned; but not necessarily by you...

The coins can be transferred from a pool to an exchange, sold for USD, then repurchased. The USD could be considered regular income as the Bitcoins weren't owned by you, as if you were a worker mining gold for a gold mining business getting paid in USD. The coins you purchase with USD won't be considered a capital gain until you sell them.

EDIT:

Bitcoin mining is not taxed on capital gains. The above approach is meaningless as Bitcoin mining is taxed as ordinary income immediately. The tax implications are more favorable for those who mine and hold.