warning signs, page-8

There are about 2-3 pretty deep mines of AB size, depth and grade that have been pretty profitable. E.g. the Kidd Creek Copper & Zinc mine in Ontario Canada, which has only 2% copper grade and 4-6% zinc. It's also deeper i.e. 3km and is owned and operated by Xstrata.

AB on grade and depth is presently uneconomic and becomes so if zinc moves above $1.10 and depends on bi-product credits from lead 3% and silver moving up in tandem. Once you have built the shaft and begun mining operations, the operations themselves could tolerate lower zinc prices.

Minmetals bought Lennard shelf just north of AB in the same basin a few years back. Most of the geology of the sub surface layers are mudstone.