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Formula: KLi2Ti(Si4O10)(OF)
Phyllosilicate (sheet silicate), trioctahedral mica group,
mica group, lithium- and
titanium- bearing mineral
Crystal System: Monoclinic
Specific gravity: 2.91 measured, 2.014 calculated
Hardness: 2 to 3
Streak: White
Colour: Colourless to white
Luminescence: Fluoresces bright yellow under short wave UV, but does not fluoresce under long wave UV
Environments
Orlovite was approved in 2009 but to date (April 2025) it has been reported only from the type locality.
Localities
At the type locality, the Dara-i-Pioz Massif, Districts of Republican Subordination, Tajikistan, orlovite was
discovered in samples collected on a moraine of the Darai-Pioz glacier. One of the characteristic features of the
massif is the wide variety of mica minerals present, including
muscovite, annite,
tainiolite, polylithionite,
sokolovaite and orlovite. Orlovite is the
titanium analogue of
polylithionite, and it is the first completely
titanian mica from the
mica group. It occurs in a rock consisting mainly of
quartz with several rare accessory minerals. The rock is composed of middle to
coarse-grained aggregates of quartz of icy appearance. The appearance of these
Si-rich rocks is very characteristic because of the presence of idiomorphic black crystals of
aegirine with brilliant facets, large violet-pink plates of
sogdianite, red-brown translucent lenticular crystals of
stillwellite-(Се), poorly-bounded crystals of pale yellow-pink
reedmergnerite, green elongated prismatic crystals of
turkestanite and large crystals of
polylithionite. In addition,
galena, calcite,
neptunite, sugilite,
pyrochlore, minerals of the
eudialyte group, tadzhikite,
baratovite, native bismuth,
sphalerite, fluorite,
fluorapatite,
fluorapophyllite,
sokolovaite,
kapitsaite-(Y), pekovite,
zeravshanite and
faizievite occurs in this rock. A characteristic feature of this
essentially quartz rock is the presence of brown polymineral aggregates (up
to 25 cm in size) consisting of pectolite,
quartz, fluorite,
aegirine, polylithionite
and other minerals.
Segregations of orlovite occur mainly in intergrowth with pectolite,
quartz, baratovite,
neptunite, leucosphenite,
zeravshanite, faizievite
and pyrochlore. Orlovite forms lamellar, colourless grains up to
2 mm in size that appear white in aggregates
(New Data on Minerals, 46. Moscow. 13-19).
The alkaline massif has boron-rich
granitoids intruding into
schists, crossed by
metasomatite and
pegmatite veins. The
pegmatites resulted from the differentiation of a silicic
melt to the point where saturation in boron is attained under vapour
unsaturation with reedmergnerite +
orthoclase / microcline /
quartz assemblage (T = 450 to 500°C, P less than 2kbar).
Note: This locality is in a very remote area with hostile actors in the area. Recent access has been by helicopter
(Mindat).
Orlovite from the Dara-i-Pioz Massif
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