|Hardness||6 - 6.5|
|Optic nature||Uniaxial -|
|Refractive index||1.560 - 1.596|
Habit: crystals are elongated parallel to the optic axes. Massive as pebles. A rare crystalline non-metamict state of ekanite has also been found.
ThCa2Si8O20: Calcium Thorium Silicate with radioactive elements present. Commonly Uranium, Iron, Lead also present. Metamict and rarer non-metamict ekanite has been found.
Green, dark brown, light brown, emerald green, also chatoyant, 4-ray, 6-ray varities also. Straw yellow when pure; dark red (due to inclusions).
Transparent to translucent.
S.G. 3.08 (impure) and 3.28 - 3.36 (pure) generally 3.28
Optic Character: DR, Uniaxial negative.
Refractive index: 1.560 - 1.568 (may also be 1.590-1.596 or 1.573-1.572) Most commonly 1.596
Maximum birefringence: 0.001 - 0.008
Ekanite may test isotropic due to metamictization.
May show lines at 630, 658 nm
UV fluorescence: generally inert
Radioactive; enough to activate a Geiger Muller Counter. Non-radioactive material also found. May test isotropic due to radioactivity.
Chatoyancy and asterism (4 or 6-pointed stars).
Heat treatment to restore crystalline state.
Brazilianite: lower S.G.; R.I., D.R.
Found as water worn pebbles; first in the gem-gravels of Sri Lanka. Also in glacial syenitic boulder.
Ehiliayagoda, near Ratnapura in Sri Lanka; Also chatoyant, 4- or 6-ray also. Also at Mt. Ste Hilare; Quebec, Canada; Central Asia; Tombstone mountains, Canada (non-metamict ekanite).