Photo of a Cut crystal of Ekanite — Photo: Geni · CC BY-SA 4.0
Ekanite
An uncommon thorium-bearing calcium silicate of the steacyite group — one of the few naturally radioactive gemstones.
Intro adapted from Wikipedia (CC BY-SA).
Ekanite is an IMA-recognized mineral species in the silicate class, with the chemical formula Ca₂ThSi₈O₂₀.
It crystallizes in the tetragonal crystal system (space group P4/mcc). It is a member of the Amorphous structural group.
Key properties: Mohs hardness 4.5–5; specific gravity 2.95–3.28; White streak; Vitreous luster; optically uniaxial.
IMA symbol Ek, IMA status: approved, named in 1961.
Detrital (Sri Lanka); in a glacial erratic syenitic boulder (Tombstone Mountains, Canada); in volcanic ejecta (Case Collina, Italy).
It is found associated with Fluorite, garnet, quartz, microcline, clinopyroxene, apatite, sodic plagioclase, hematite, thorogummite, zircon, titanite (Tombstone Mountains, Canada).
In honor of the mineral's discoverer, F.L.D. Ekanayake, of Colombo, Sri Lanka.