My knowledge was pretty limited on this topic so I was blown away by Mike's description of the nature and origin of these complex systems.
The Noril'sk-Tanakh deposit in Siberia is a mafic sill complex in continental flood basalts with amazingly rich sill tubes that are 300-500 m thick, 500 -1,500 m wide and 15 - 20 km long. Massive sulfide concentrations form below the keels or axes of these tubes with local copper bodies a km across and 50 m thick at 25% Cu!
Mike's pictures of blogs, nuggets, and bands of pure metal elicited oohs and aahs from my tablemates.
There was a good discussion afterwards about the structural controls on the origin of these tube deposits and the lack of structural geologic analyses of these systems.
Mike [left] accepts a mineral specimen from the Ray mine and the thanks of AGS Program Chair Bob Kamilli.
On a tangential note, the dinner of orange roughy and grilled asparagus was sensational and is the best I can remember at a dinner meeting. Everyone else at our table raved about it as well. Bravo to the Sheraton Four Points in Tucson!