“…The Roberts Mountains Formation ranges in age from Silurian to Devonian, whereas the overlying Popovich Formation is Devonian. The Roberts Mountains Formation was studied regionally by Mullens (1980) to identify its stratigraphic and petrologic characteristics and, in particular, how these features may relate to ore deposition. Recently, however, it became apparent that a modern petrographic study of specimens from this formation from the Carlin mine and neighboring area might disclose additional information about favorability of these rocks as host rocks for ore. We used scanning electron microscopy coupled with energy-dispersive X-ray analysis and transmitted-light microscopy to examine the mineralogical and textural characteristics resulting from diagenesis, metamorphism, and hydrothermal alteration associated with gold deposition in these rocks.…”