Independent mine consultant Tim Oliver described Rubicon Minerals' Phoenix mine as "toast" in CEO Chat on Oct. 5 and this morning he appeared on BNN to elaborate.

Shares of Rubicon Minerals (RMX-T) have been hammered, dropping from $1 to 0.20 in the past month after environmental problems, a temporary shutdown order and finally, Tuesday's announcement that it was shutting down operations while it gets to know the deposit better. The company has laid off more than 300 employees and contractors.

Oliver, an engineer, told BNN's Andrew Bell that Rubicon's fatal flaw was to build a mine based on a preliminary economic assessment rather than more detailed engineering studies.

The Phoenix project started with a "sloppy" resource estimate and went downhill from there. The Red Lake, Ontario deposit has a difficult geology, with narrow veins and a nugget effect making continuity difficult to measure.

"That's the first thing ... You can't engineer a good mine from a lousy resource."

A warning sign was the first gold pour, Oliver commented, which was "more theatre than anything economic."

Tim is one of several regulars who add value at CEO Chat, the investment conference in your pocket. His blog is called Mining's Black Box.

This is not investment advice and all investors should do their own due diligence. Rubicon Minerals proves it.