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Formula: Ti2ZrO6
Simple oxide of titanium and
zirconium,
samarskite group,
columbite supergroup
Crystal System: Orthorhombic
Specific gravity: 4.6 measured, 4.77 calculated
Hardness: 6½
Colour: Black, blackish brown
Luminescence: Not fluorescent under UV
Environments
Localities
At the Atlantis II Fracture Zone, Southwest Indian Ridge, Indian Ocean, srilankite in a
gabbroic vein cutting a
serpentinised
peridotite was collected using submersible SHINKAI 6500 of the
Japanese Marine Science Technology Center. Srilankaite occurs in small patches less than 30 microns across,
always co-existing with ilmenite and
rutile. Zircon,
apatite and phlogopite also
occur as accessory minerals in the vein.
The srilankite appears to have co-crystallised with ilmenite and
rutile from melts rather than through metamorphic recrystallisation.
Geochemical interactions between peridotite and melt in the upper
mantle may effectively concentrate incompatible elements in a modified melt, which may precipitate srilankite
directly
(AM 89.759-766).
At the type locality, Rakwana, Ratnapura District, Sabaragamuwa Province, Sri Lanka, srilankite occurs in
pebbles from a placer gemstone mine. The pebbles are mainly zirconolite
and baddeleyite with minor amounts of
geikielite, spinel and
perovskite. Srilankite occurs as inclusions less than 1 mm across
in such pebbles
(AM 69.210-215).
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