The Coles Hill uranium deposit is located in

Pittsylvania County, Virginia Pittsylvania County is a county located in the Commonwealth of Virginia. As of the 2020 United States Census, the population was 60,501. Chatham is the county seat. Pittsylvania County is included in the Danville, VA Micropolitan Statistical A ...

in the Smith River

allochthon upright=1.6, Schematic overview of a thrust system. The hanging wall block is (when it has reasonable proportions) called a nappe. If an erosional hole is created in the nappe that is called a window (geology)">window. A klippe is a solitary out ...

of southern Virginia. The deposit is located east of US Highway 29 between the towns of Chatham and Gretna, Virginia, divided into a north and south ore body. A part of Virginia's Western Piedmont Province, the uranium deposit is bounded by the Chatham fault to the east, where it borders the

Triassic The Triassic ( ) is a geologic period and system (stratigraphy), system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago (Year#Abbreviations yr and ya, Mya), to the beginning of the Jurassic Period 201.36 ...

Danville basin. Uranium minerals are found in the footwall of the Chatham fault, in healed fractures where apatite crystallized from high-temperature hydrothermal water in the Leatherwood

granite Granite () is a coarse-grained ( phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies under ...

mylonite Mylonite is a fine-grained, compact metamorphic rock produced by dynamic recrystallization of the constituent minerals resulting in a reduction of the grain size of the rock. Mylonites can have many different mineralogical compositions; it is a ...

. The site was discovered during uranium prospecting in the 1970s, inspired by the Ambrosia Lake deposit in Canada, with exploration led by the Marline Oil Corporation. Uranium is found within a structural trap, surrounded by biotite

gneiss Gneiss ( ) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. Gneiss forms at higher temperatures a ...

, with staining from hematite overlying the Fork Mountain

schist Schist ( ) is a medium-grained metamorphic rock showing pronounced schistosity. This means that the rock is composed of mineral grains easily seen with a low-power hand lens, oriented in such a way that the rock is easily split into thin flakes ...

. Hematite staining on the ground surface is related to the weathering of the Fork Mountain schist. The exact origin of this uranium deposit is unclear. One model suggests that uranium was dissolved and "mobilized" from the neighboring Triassic basin by rainwater, while a different interpretation suggests mineralization occurred because of hydrothermal fluids flowing through the rock during the emplacement and cooling of the Leatherwood granite.

References

{{Geology of the United States by political division Geology of Virginia

Virginia Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth ar ...