Some of the largest gold nuggets found in Alaska are from the district, which lies along the Yukon River.
Cassiterite, platinum, scheelite, allanite, and native bismuth have been recovered along with gold from placer mines in the district.
Possibly a quarter (approximately 98,000 ounces) of all the gold recovered from the Ruby district before 1960 came from Poorman Creek.
Rhyolite porphyry (the host rock of Donlin and other important hardrock gold deposits) is reported to underlie the creek locally.
Bedrock surrounding Poorman Creek is Paleozoic phyllite and quartzite, but the stream flows within 2 miles of the Poorman fault, a major tectonic feature juxtaposing Innoko terrane chert and slate with the Ruby terrane phyllite, quartzite, marble, limestone, and Tertiary volcanic rocks.