That's good. However, I'm pretty sure that's a mistake in the article, specifically in this line:

So far the work has been done to 10 million to 20 million tonnes of core sample.

I'm certain it's not 10 million to 20 million tonnes of samples. There would be nothing left to mine.

Maybe 10m to 20m kilograms? I was also trying to figure out if it was a length that got misquoted, ie. maybe 10 thousand to 20 thousand metres of core sample.

Core sample is certainly heavy; it's rock. But with the holes averaging maybe 1000m each, they'd be using the relevant parts of the samples from maybe thirty or forty holes.

The only other logical possibility is "the work has been done to the core samples from a body of ore that measures between 10m and 20m tonnes."

Perhaps someone could email Moe Lavigne to clarify. Actually, I'll do that right now, and let you know if I hear anything.