For many hard rock mines with near surface deposits, the surface crown
pillars form the first line of protection for the immediate underground
workings. Underground stopes are typically contained by crown pillar,
which protects the level above, rib pillars, and a sill pillar through which
the ore collection system is cut. This paper discusses the mining of these
pillars, with particular emphasis on the overall stability of the mined out
upper part of the mine areas. An area of interest is located in the Canadian
Shield, where the mining has progressed below four thousand foot level
in the ultramafic high grade sulphide type of orebody.