Thick sequences of gold-bearing quartzite conglomerate occur in latest Cretaceous and Tertiary formations and in Quaternary gravels derived from them in northwest Wyoming. Analyses of about 1,200 samples (by a new cyanide-atomic absorption method) and 750 panned concentrates representing 53 localities show the following averages in parts per billion and cents per cubic yard: Harebell Formation (latest Cretaceous), 65 (11 cents); Pinyon Conglomerate (Paleocene), 86 (14 cents); Fort Union Formation (Paleocene), 35 (6 cents); conglomerate of earliest(?) Eoceneage, 94 (14 cents);WindRiverFormation(early Eocene),222 (35 cents); Pass Peak Formation of Eardley and others (middle(?) Eocene), 47 (8 cents); Miocene(?) conglomerate, 65 (11 cents); Quaternary deposits, 103 (16 cents). These values are for the bulk rock although the gold is largely confined to sandstone layers and the sandy matrix of the conglomerates, which contain various proportions of pebbles and cobbles. The conglomerates were derived chiefly from Precambrian and possibly Paleozoic quartzite in a now-buried uplift northwest of the Teton Range. Although the grade is low, the volume, 50 cubic miles or more, is so large as to constitute a resource of enormous proportions. The presence of above-average grades in some localities suggests that local concentrations may exist and makes the conglomerates and their derivatives attractive for additional prospecting.

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