The mineral was discovered in Chamouni by Pictet in 1787, and was named Pictite by Delamètherie (1797). In 1795 Klaproth analysed a specimen from Passau, and, observing the presence of titanium (which he had just discovered in rutile), proposed the name Titanite. The mineral described by de Saussure (1796) as ‘Schorl rayonnante,’ and afterwards by Hauy (1801) as Sphene (σφήν = a wedge), was shown to be identical in composition with titanite by Cordier, and also by Klaproth (1810); the crystallographic identity was proved by G. Rose (1820).
On account of the difference in colour and composition, a large number of varieties are distinguished. The ordinary yellow and brown varieties are known indifferently as sphene or titanite. Ligurite has an apple-green colour; Semeline is a greenish form named from a fancied resemblance to flax seed. Lederite is a brown variety of tabular habit; Greenovite is rose-coloured, and contains manganese. Alshedite and Eucolite-Titanite are rich in the trivalent metals; Grothite is a brown variety containing a considerable percentage of ferric iron. Yttrotitanite, which contains a high proportion of rare earths, is usually treated as a separate species (see [above]). Titanomorphite and Leucoxene are white amorphous varieties chiefly produced by alteration of rutile and ilmenite.
Titanite is a fairly widespread mineral; as an accessory rock constituent it is common in the massive plutonic rocks in tiny crystals, readily distinguished under the microscope by the high refraction and birefringence, whilst in large embedded crystals it occurs in many granular limestones, and in plutonic acid, as well as in some metamorphic rocks. In good crystals it is found in many parts of Switzerland and the Alps, in Dauphiné, the Tyrol, Piedmont, the Urals, South Norway, and other European localities; it is also widely distributed in the United States and Canada.
The mineral is important as a valuable source of titanium.
The class of Titano-silicates is a very large one, and might be extended almost at will by the inclusion of the numerous silicates which contain titanium. Owing to the frequency with which small quantities of silica are replaced by titanium dioxide, almost all the commoner silicate minerals contain the latter oxide, so that titanium is one of the most widely distributed of the elements. Relatively very few, however, of the titanium-bearing minerals contain the element in considerable quantities, and only two or three have any importance as commercial sources of titanium compounds.
Only those additional titano-silicates which contain titanium as an important constituent are mentioned below; short accounts will be found in the alphabetical [list].
Johnstrupite, Mosandrite, Rinkite, Rosenbuschite and Tscheffkinite are complex titano-silicates containing yttrium or cerium metals.
Astrophyllite, Leucosphenite, Molengraafite, Neptunite and Rhönite are complex titano-silicates free from rare earth elements.
Benitoite is a simple titano-silicate of barium; Ænigmatite and Narsarsukite contain iron and sodium; Lorenzenite has sodium and zirconium. Schorlomite is a titaniferous garnet. A variety of olivine rich in titanium (Titanium Olivine) is also known.