Is it actually gold that's being traded, or papers/promises/options/whatever-else-but-physical-gold saying 'x amount of gold' is actually traded?

Well, physical Bitcoins aren't being traded either.

Because there aren't physical Bitcoins.

Actual custody is being traded though.

Same for gold (again legally, not physically).

For gold, typically ownership is traded, not custody.

That could be the same gold being traded multiple times per day. What % of all gold extracted from the ground is traded annually?

Why does it matter if it's the same gold?

Say a 100 people each own a 100 gold pieces. And they all buy and sell 100 gold pieces worth of goods and services per day.(10,000 gold pieces are traded) Why would it matter if this is physically the same gold coin traded 10,000 times or 10,000 gold coins being traded once?

Because the WSJ article specifically talks about the number of bitcoins traded as a percentage of the whole number of coins mined. This is why I keep asking for this percentage for other assets like gold and stocks.

On options maybe.