banded chert magnetite iron formation:

(geology) A sedimentary mineral deposit consisting of alternate silica-rich (chert or quartz) and iron-rich layers formed 2.5-3.5 billion years ago; the major source of iron ore.

My interpretation is they found traces of gold which are unexpected in this type of formation but not enough to report the results in g/t. In other words, we did not hit any significant nickel or copper or gold, but we can smell it, so its got to be around here somewhere.

BK