Hypothetical question: Let's say that during the last financial...

Hypothetical question:

Let's say that during the last financial year you had zero income. But during that time you sold shares and had a capital gain of $10,000.

Is this $10,000 counted as income for tax purposes?
The tax free threshold is about $18,000, so does this mean you pay no tax on the $10,000 capital gain during that financial year?
Or do you still have to pay capital gains tax on that $10,000 even though you earned less than $18,000?