Thorium–bitumen mineralization in Silurian sandstones, Welsh Borderland

Abstract
The Llandovery Folly Sandstone near Presteigne, Powys, contains disseminated thorium mineralization. The thorium occurs as inclusions of thorite and thorianite within sub-millimetre-scale bitumen nodules throughout the sandstone. The nodules grew replacively in situ. The two square kilometres outcrop/subcrop of the sandstone may contain over 500 tonnes thorium.