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Formula: CaTi(SiO4)O
Nesosilicate (insular SiO4 groups), titanium-bearing mineral
Varieties
Keilhauite is an yttrium-bearing variety of titanite
Triclinic titanite is a variety of titanite with a triclinic symmetry, first recorded from the Heftetjern
pegmatite, Tørdal, Drangedal, Telemark, Norway
Crystal System: Monoclinic
Specific gravity: 3.48 to 3.6 measured, 3.53 calculated
Hardness: 5
Streak: White
Colour: Brown, green, yellow, red
Solubility: Insoluble in water, nitric and sulphuric acid; slightly soluble in hydrochloric acid
Common impurities: Fe,Y,Mn,Al,Ce,Sr,Na,Nb,Ta,Al,Mg,V,F,Zr,Sn
Environments:
Igneous environments (common)
Pegmatites
Carbonatites
Sedimentary environments (rarely)
Metamorphic environments
Hydrothermal environments
Titanite occurs as a primary
titanium mineral in small crystals as a
common accessory in intermediate and quartz-rich plutonic rocks, in
pegmatites and
rarely as a detrital mineral in some sedimentary deposits.
In igneous rocks it is found mainly in diorite,
syenite and granite,
and it is much less common in volcanic rocks
(Lauf p74).
In metamorphic rocks titanite is found primarily in gneiss and
schist that is rich in ferromagnesian minerals. It is also found in
skarn and in calcium-rich Alpine fissures
(Lauf p75).
In regional metamorphic environments it occurs
as crystals of considerable size. It is a mineral of the
prehnite-pumpellyite,
greenschist,
amphibolite and
blueschist facies.
Associated minerals are iron ores,
pyroxene,
amphibole, scapolite,
zircon, apatite,
feldspar and quartz.
Hydrothermal titanite is a common alteration product of
titanium-bearing minerals such as
ilmenite, which may be directly replaced by titanite, or it may
contribute titanium to hydrothermal fluids allowing growth of
titanite in nearby vugs or pore spaces. It forms over a large temperature range, at least
200oC to 400oC, and may be associated with
actinolite, biotite,
calcite, chlorite,
clinopyroxene, epidote,
garnet,
quartz and wollastonite
(AofA).
Titanite may be found in
granite,
granodiorite,
diorite, syenite,
nepheline syenite,
gneiss,
schist and
limestone.
Alteration products of titanite include anatase, sometimes mixed with
quartz, and rutile. Replacement of detrital
titanite by rutile, calcite and
quartz under authigenic conditions in
limestone has been reported
(Lauf p76).
Localities
The Capelinha district, Minas Gerais, Brazil, is made up of low-grade metamorphic
mica
schist and phyllite
with layers of
quartzite. The titanite-bearing vein is a
skarn made of feldspar,
quartz, epidote,
hornblende, titanite and minor
magnetite
(Lauf p83).
At lots 10 and 11 of concession 1, Bathurst Township, Lanark County, Ontario, Canada (DeWitts corner), the deposit is
located in the Grenville Geological Province, which consists mostly of
marble, gneiss, and
quartzite.
Syenite-migmatite was
also reported in the area where the vein-dikes are located. Characteristic features of the vein-dikes include the
fact that perfectly formed euhedral crystals of different minerals can often be found floating in
calcite with no points of contact with the walls. Sometimes these crystals
have inclusions of calcite, irregular or rounded in shape. It has been
argued that at least some of the vein-dikes were formed as a result of melting of Grenville
marble.
Titanite is a rare mineral at DeWitts Corners. It occurs as short-prismatic crystals to 8 mm together with
diopside and is most commonly found on specimens on, or adjacent to, the
wallrock of the vein-dikes
(R&M 97.6.556-564).
At Mont Saint-Hilaire, Quebec, Canada, titanite occurs in
nepheline syenite
(Lauf p74).
In Ontario, Quebec, Canada, titanite is widespread in the Grenville
marbles
(Lauf p75).
Near El Alamos, Baja California, Mexico, titanite occurs in a
granite
pegmatite
(Lauf p74).
Near Arundal, Norway, titanite occurs in a granite
pegmatite
(Lauf p74).
At Mulla Ghori, Zagi mountains, Pakistan, titanite occurs in an alkaline
pegmatite
(Lauf p74).
At the Saranovskiy mine, central Urals, Russia, chromium-rich
titanite occurs with
chromium-rich amesite,
chromite and other species
(Lauf p74).
In the Khibiny and Lovozero massifs, Kola peninsula, Russia, titanite occurs in
nepheline syenite
(Lauf p74).
At Land's End, Cornwall, England, UK, titanite occurs in schist
(Lauf p75).
In the San Jacinto mountains, Riverside county, California, USA, titanite with inclusions of
andesine and quartz occurs in
granodiorite
(Lauf p74).
At the Crestmore quarry, Riverside county, California, USA, titanite occurs in
schist
(Lauf p75).
At the Ojibway No. 1 mine, Ojibway Mine, Ojibway, Keweenaw county, Michigan, USA, a
0.47 mm gemmy titanite crystal has been found on a substrate of crystallised
chamosite
(R&M 97.4.358).
Amity, Town of Warwick, Orange county, New York, USA, is an area of
granite intrusions into
marble and associated
gneiss. The marble is
mostly composed of white crystalline calcite that often has small flakes
or spheres of graphite and
phlogopite. Titanite occurs as opaque, classic wedge-shaped
brown individual crystals, associated with scapolite and
augite. Crystals are relatively large for the species, in some cases
measuring more than 5 cm
(R&M 96.5.440).
The Purple Diopside Mound, Rose Road, Pitcairn, St. Lawrence county, New York, USA, is situated in
marble. The development of veins of large crystals probably occurred
as a result of fluid penetration from a concurrent intrusion. Many of the minerals of interest to collectors formed
during this primary event, with additional species resulting
from the
subsequent alteration of scapolite. There seems to be little, if any,
secondary, late-stage mineralisation present.
Titanite occurs sparingly as flattened, lustrous, black crystals to approximately 4 cm, associated with
scapolite and sometimes as isolated crystals in
calcite. Millimetre-sized black titanite crystals occur with
diopside on the steep hill behind the Purple Diopside Mound
(R&M 96.6.552).
At the Pyrites Mica mine, St Lawrence county, New York, USA, titanite is associated with
diopside and meionite
(R&M 93.4.343).
Near the crest of the Blue Ridge, Roanoke county, Virginia, USA,
pseudomorphs of
anatase after titanite have been reported
(Lauf p76).
Alteration
lawsonite and titanite to zoisite,
rutile, quartz and H2O
3CaAl2(Si2O7)(OH)2.H2O + CaTi(SiO4)O →
2Ca2Al3[Si2O7][SiO4]O(OH) + TiO2 + SiO2
+5H2O
The lawsonite -
titanite assemblage is characteristic of the lower
blueschist facies
(Lauf p76).
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