CCZ - from 6 cents to 50cents ?, page-14

And, as a side note, sometimes high grade isn't the be all and end all! A really cool deposit to look into is the Admiral Bay Zinc Project:

"The Admiral Bay deposit, which was discovered by accident during petroleum exploration in 1981, is one of Australia’s largest undeveloped zinc-lead resources, but the depth of deposit (over a kilometre) is a major impediment to development." - Geosciences Australia

Metalicity used to have a video on their website showing how they were planning to sink shafts and mine it with longwall mining equipment like they do for coal. I can't find the vid unfortunately but still cool to note