Difference between revisions of "Ekanite"
(addition from Chaman Golecha (id:93)) |
(added phenomena) |
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==Other properties== | ==Other properties== | ||
Radioactive; enough to activate a Geiger Muller Counter. Non-radioactive material also found. May test isotropic due to radioactivity. | Radioactive; enough to activate a Geiger Muller Counter. Non-radioactive material also found. May test isotropic due to radioactivity. | ||
+ | |||
+ | ==Phenomena== | ||
+ | Chatoyancy and asterism (4 or 6-pointed stars). | ||
==Treatments== | ==Treatments== | ||
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==Simulants== | ==Simulants== | ||
− | + | [[Brazilianite]]: lower S.G.; R.I., D.R. | |
==Ocuurence== | ==Ocuurence== | ||
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Found as water worn pebbles; first in the gem-gravels of Sri Lanka. Also in glacial syenitic boulder. | Found as water worn pebbles; first in the gem-gravels of Sri Lanka. Also in glacial syenitic boulder. | ||
− | Geographical locations<br /> | + | Geographical locations:<br /> |
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). | 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). |
Revision as of 05:12, 12 September 2007
Ekanite | |
---|---|
Chemical composition | ThCa2Si8O20 |
Crystal system | Tetragonal |
Habit | Elongated, pebbles. |
Cleavage | None |
Hardness | 6 - 6.5 |
Optic nature | Uniaxial - |
Refractive index | 1.560 - 1.596 |
Birefringence | 0.001-0.008 |
Dispersion | Low |
Specific gravity | 3.28 |
Lustre | Vitreous |
Contents
Crystallography
Tetragonal system.
Habit: crystals are elongated parallel to the optic axes. Massive as pebles. A rare crystalline non-metamict state of ekanite has also been found.
Chemical composition
ThCa2Si8O20: Calcium Thorium Silicate with radioactive elements present. Commonly Uranium, Iron, Lead also present. Metamict and rarer non-metamict ekanite has been found.
Diagnostics
Color
Green, dark brown, light brown, emerald green, also chatoyant, 4-ray, 6-ray varities also. Straw yellow when pure; dark red (due to inclusions).
Diaphaneity
Transparent to translucent.
Specific gravity
S.G. 3.08 (impure) and 3.28 - 3.36 (pure) generally 3.28
Refractometer
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.
Spectrum
May show lines at 630, 658 nm
Luminescence
UV fluorescence: generally inert
Inclusions
Crystalline inclusions
Other properties
Radioactive; enough to activate a Geiger Muller Counter. Non-radioactive material also found. May test isotropic due to radioactivity.
Phenomena
Chatoyancy and asterism (4 or 6-pointed stars).
Treatments
Heat treatment to restore crystalline state.
Simulants
Brazilianite: lower S.G.; R.I., D.R.
Ocuurence
Geological occurrence:
Found as water worn pebbles; first in the gem-gravels of Sri Lanka. Also in glacial syenitic boulder.
Geographical locations:
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).