vino - we won't know anything for sure until we get assays. From what I have been reading on these Carlin-type deposits, the gold is fine-grained and not typically visible. They are in to the right rocks, though. The silty limestone seems to be key. Here is a piece from a paper on the Turf Deposit:

"These deep, high-grade gold deposits range in size from 300,000
ounces (9.3 t) at Four Corners to 3 million ounces (93 t) of gold
resource at West Leeville (Jackson and others, 1997). These
deposits share a variety of common characteristics such as: (1)
impure carbonate host rocks in the lower plate of the Roberts
Mountains thrust, specifically the Popovich limestone and
Roberts Mountains Formation; (2) decalcification, silicification,
and carbon flooding; (3) multi-episodic disseminated pyrite;
(4) abundant antimony, arsenic, and mercury associated with
ore-grade gold and (5) sulfidic, refractory gold ore with grades
that average approximately 0.40 opt (13.7 g/t)."

http://www.nbmg.unr.edu/dox/b111/turf.pdf