The Rottenstone deposit is a mineralized ultramafic sill (harzburgite-orthopyroxenite). Mineralization occurs as semi-massive to massive, net textured sulphide ore comprised of pyrrhotite, chalcopyrite and pentlandite. The Rottenstone ore body is unique; the contained precious metal content is higher grade than ores of most deposits of this type and the high sulphide content of the ore (estimated to be 40-60%) in what is interpreted to be a small ultramafic body (sill) is very unique. The exploration model / deposit type that defines the Rottenstone deposit and mineralization is a deep-rooted, mantle derived, magmatic, ultramafic intrusive body that has traversed to the crust and settled in deformed supracrustal meta-sedimentary rocks. The extremely high Ni-PGE grade of Rottenstone ore is a function of the R factor, specifically a high R factor. The R factor is; the ratio of, mass of silicate magma to sulphide melt. To achieve the high Ni-PGE grades; a direct result of the high sulphide content of the ore, the sulphides had to have the chance to equilibrate with a large volume of magma enabling the sulphides to scavenge Ni and PGE’s. The high sulphide content of the Rottenstone ore is a function of a sulphide rich, very large master magma chamber (of high R factor) existing nearby (personal communication; Dr. Larry Hulbert – world renowned expert, magmatic nickel deposits). It is believed the Rottenstone deposit is a small sill-like body that is one of several similar size and larger mineralized ultramafic bodies emanating from a very significant magma chamber occurring within the confines of Fathom’s Rottenstone property.
In simple terms it just does not make sense to have such a high grade deposit of this type that is only the size of the of the original Rottenstone deposit (originally interpreted to be approx. 50m diameter). A much larger source must occur nearby or at depth.