Saturday, September 20, 2008

An exquisite and rare lemon-yellow or green gemstone

Sphene (or Titanite) is a rare collector gemstone with an unusually high refractive index and a hardness of 5 -5.5. Sphene is named from the greek word for wedge, because of its typical wedge shaped crystal habit Because of its high dispersion and refractive index, a well cut sphene can display stunning brilliance. Sphene is somewhat soft and as a result more suitable as a pendant than as a ring stone.

Sphene is widely distributed as an accessory mineral, particularly in coarse-grained igneous rocks such as syenite, nepheline syenite, diorite and granodiorite. It occurs similarly in schists or gneisses and in some metamorphosed limestones. Collectors appreciate its crystals, in which twinning is common, as well as the striking appearance of the faceted gemstones.

Thursday, September 11, 2008

Amazing color and beautifully cut trillion sphene

Sphene is a fairly rare stone and is classed as collector's stone and this 16.27 ct stone from Madagascar is a brilliant gem, with a diamond like luster and fire.

Pictured gemstone is perfect for pendant and maybe for the designer ring, if you don't go out and chop wood with it on. Like tanzanite, sphene won't take rough wear.

If used for the pendant, where the light can react with it best anyway, you will have very unusual and rare piece of fine jewellery.

Friday, January 11, 2008

Gemmy sphene from East Tyrol, Austria

Only a few miles over a high mountain ridge south of the famous Habach valley, East Tyrol between the Grossglockner and the Grossvenediger is not so well known among the average mineral and gem collector.

A trip usually begins at one of the small towns and hamlets in the Virgen valley or Hinterbichl, which lies at the western end of the valley. From there, it goes straight north into the Dorfer valley.

At the Mullwitz site, clefts in gneiss harbor 1 cm crystals of golden-brown anatase on quartz and loose crystals in chlorite, but the best finds are sphene (titanite) crystals in dark brown color and up to 5 cm in size.

At Wallhornalpe occur rose anatase, apatite with amianth, and pericline on actionlite schist. Additionally are found brookite, calcite, nice epidote, light green diopside, hessonite, magnetite, pyrite, and prehnite in eclogit. Some gemmy sphene had been collected also. In clefts of praissinite rock on contact with marble occur clear needles of scapolite in quartz. Finds in the Maurer valley contain red sphene crystals and clinozoisite with laumontit 2 cm in size.

Further east into the Kalser valley we have reached one of the more famous and well known locations in East-Tyrol, the Lapperwitzbach graben. Some of the best sphene of the Alps has been collected from there with crystals up to 7.5 cm in size, translucent and greenish-brown in color. Unfortunately, this site was mostly destroyed by collectors looking only for big quartz crystals.