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Formula: K2NaTi2O(OH)Si4O12
Inosilicate (chain silicate), single chains, batisite group,
titanium-bearing mineral, Forms a series with
batisite
Crystal System: Orthorhombic
Specific gravity: 2.968 measured, 3.194 calculated
Hardness: 6½
Colour: Dark brown
Common impurities: Zr,Al,Fe,Ta,Mn,Mg,Ca,Cl,H2O
Environments
Pegmatites
Hydrothermal environments
Localities
At the type locality, Apatitovyi Tsirk, Rasvumchorr Mine, Rasvumchorr Mt, Murmansk Oblast, Russia, shcherbakovite
has been found in a pegmatite in shallowly dipping hydrothermal
veins of semitransparent columnar natrolite, cutting
leucite-normative kalsilite -
nepheline rischorrite. The
veins vary from 3 to 20 cm in thickness and have selvages 3 to 5 cm wide composed of green acicular
aegirine and yellow K-feldspar.
Shcherbakovite forms prismatic crystals ranging from a few mm to 6 cm in length, embedded in
natrolite. The paragenesis includes relatively large well-shaped single
prisms of black aegirine–diopside,
slightly corroded blocky orthoclase, euhedral 1 to 2 cm crystals of
strontium-bearing fluorapatite,
anhedral colourless titanite and rare grains of
pyrrhotite and chalcopyrite
and laths of manganese-bearing
pectolite up to 20 cm in length, which in places have been completely
replaced by a fine-grained mixture of Fe–Mn oxides.
The majority of the shcherbakovite-bearing veins were affected by faulting, and were injected by additional
hydrothermal solutions, which resulted in deposition of spherulites of
barylite 1–5 mm across and caused fragmentation of crystals and coating of
large shcherbakovite crystals by an unidentified enamel-like yellowish silicate phase, in addition to the
alteration of manganese-rich
pectolite, titanite and
apatite. The most homogeneous and transparent crystals of
shcherbakovite occur on slightly corroded surfaces of K-feldspar.
Other associated minerals include albite and
astrophyllite
(CM 41.5.1193-1201, HOM).
Shcherbakovite from Rasvumchorr Mt -
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