Titanite

nesosilicate

primary

Formula: CaTi(SiO4)O nesosilicate (insular SiO4 groups)
Specific gravity: 3.48 to 3.60
Hardness: 5
Streak: White
Colour: Brown, green, yellow, red
Solubility: Insoluble in water, nitric and sulphuric acid; slightly soluble in hydrochloric acid
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 200 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).

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 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 granite pegmatite (Lauf p74).

Near Arundal, Norway, titanite occurs in 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 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).

Common impurities: Fe,Y,Mn,Al,Ce,Sr,Na,Nb,Ta,Al,Mg,V,F,Zr,Sn

Back to Minerals