Three uranium-containing minerals, tyuyamunite (pronounced
tyew-yuh-moon-ite), possibly carnotite, and metatorbernite, have been
found in Missouri but none has been mined commercially. Tyuyamunite and
carnotite are canary yellow powdery minerals so similar in appearance
they can be differentiated only by chemical and x-ray properties. Both
minerals contain uranium, vanadium, oxygen, water, and one other
element, which, if it is calcium, the mineral is tyuyamunite, but if it
is potassium the mineral is carnotite. The canary yellow color referred
to is distinctly different from the brownish or reddish yellow color of
iron oxide minerals. These yellow uranium minerals have been found near
Ste. Genevieve along cracks in limestone and in the black shale above
the limestone, and in dark, sandy shales near Shelbina, and elsewhere
north of the Missouri River.
Black shales (high in organic matter) of marine origin are the most
highly radioactive, whereas black shales deposited on land (as with
coal), and all shales of other colors are usually lower in
radioactivity.
Metatorbernite is a soft, pale apple-green scaly mineral that has been
found in paper-thin cracks in flint fire clay deposits. It contains
uranium, copper, phosphorus, oxygen, and water. All of these uranium
minerals activate a Geiger counter.