[mass noun] A greenish-yellow or brown mineral consisting of a silicate of calcium and titanium, occurring in granitic and metamorphic rocks in wedge-shaped crystals.→ titanite
- ‘The main constituent phases of these rocks are plagioclase, hornblende, pyroxene, quartz and K-feldspar, and accessory phases include magnetite, sphene, zircon and apatite.’
- ‘Titanium resides principally in heavy minerals: ilmenite, rutile, anatase and sphene, whereas Zr is located predominantly in zircon.’
- ‘Ilmenite is now largely preserved as skeletal crystals in which exsolved magnetite lamellae have been altered, and the ilmenite itself partly altered to sphene.’
- ‘How about sphene versus titanite, or celestine versus celestite?’
- ‘One of my favorite gems is sphene, or more properly, titanite.’
Early 19th century: from French sphène, from Greek sphēn wedge.