The sheet of rock of the Golden Mile vein visualized is 2530m across by 1000m deep. But the 1000m seems much larger than the 2530m. The true picture should be 2.5 times wider. And the ultimate picture will be 5000m when the extension on the other side of the lake is added - that picture would be 5 times as wide.
And the sheet can extend down 5000m or more. And that's just one vein.