As far as I know MMI isn't being used by NOT. It was used by Probe on their property just north of Eagle 1.

MMI is used to detect trace mineralization that was brought to surface by water circulation. To work, fluids have to come in contact with a deposit (or the plume from the deposit) and make their way to the surface. Water comes in contact with the deposit by the deposit being exposed at the rock/overburden interface or by faults, shears, fractures that provide an opening for water to migrate/circulate through. Over a long time very trace mineralization gets concentrated by root systems etc. The plants grow, die and decay (repeatedly) and the mineralization gets concentrated due to leaching at the interface between the decayed vegetation and inorganic soil.

Like all tools it has its place and like most exploration tools its one that is used to narrow down the target area so that you can spend your drilling dollars wisely.

... Been There (hates sampling dirt, especially in swampy areas)