Ekanite is an uncommon silicate mineral with chemical formula Ca2ThSi8O20 or (Ca,Fe,Pb)2(Th,U)Si8O20.

Most ekanite is mined in Sri Lanka, although deposits also occur in Russia and North America.

Clear and well-colored stones are rare as the radioactivity tends to degrade the crystal matrix over time in a process known as metamictization.

[5] In Sri Lanka the mineral specimens occur as detrital pebbles.

In the Tombstone Mountains of Yukon, Canada, the mineral is found in a syenitic glacial erratic boulder.