Sphene is also known as "titanite" due to its titanium content. They are yellow, orange, brown or green gems with many gradations between those colors. The usual colors are created by iron and rare-earth element impurities. Sphene is found primarily in Madagascar, Mexico, Canada and, historically, in Austria. Although reasonably available in the marketplace, it is virtually unknown to the general public.
The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.
|Crystallography||Monoclinic. Crystals often wedge shaped, well formed, flattened, prismatic; also massive, compact.|
|Colors||Colorless, yellow, green, gray, brown, blue, rose red, black. Often zoned. Color correlates with Fe content: green and yellow due to low Fe; brown and black due to high Fe.|
|Luster||Adamantine to resinous.|
|Cleavage||Distinct 1 direction. Brittle.|
|Stone Sizes||Sphene is very rare in clean stones over 5-10 carats. Even a 5-carat flawless gem is considered a rare and fine stone. Indian material generally cuts to about 10 carats, Madagascar material to perhaps 15 carats, and Brazilian yellow stones over 5 carats are scarce. Sri Lankan gems are mainly under 10 carats. Burmese stones over 20 carats are known, but Baja, Mexico, has the potential for producing some of the largest faceted gems. Chrome sphene of fine color is extremely rare, especially over 2-3 carats. Smithsonian Institution (Washington, D.C): 9.3 (golden, Switzerland); 8.5 (brown, New York); 5.6 (yellow-brown, Mexico). Private Collection: 63 carats (green); 106 (intense dark green, from India, square emerald-cut and near flawless with enormous dispersion— by far the world’s largest cut sphene). Devonian Group (Calgary, Alberta, Canada): 4.95 (red!). National Museums of Canada (Ottawa, Ontario): 50.75 (green, Brazil, very fine).|
|Spectral||Sometimes see "didymium" or rare earth spectrum. This is especially distinctive in Sri Lankan gems (sharp lines at 5860, 5820, 5300. and others).|
|Special Care Instructions||See text|
|Pleochroism||Moderate to strong: a= pale yellow; β= brownish yellow; γ= orange-brown. Sometimes (blue crystals): colorless/blue.|
SPHENE (= TITANITE)
Optics: a = 1.843-1.950; β= 1.870-2.O34; γ=1.943—2.l 10.
Biaxial (+), 2V I 1’7-40°; lower indices with lower Ti content.
Occurrence: Sphene occurs as an accessory mineral in igneous rocks, and in metamorphic rocks such as schist and granite, often in fine crystals.
New York; Canada: brown and black crystals.
Madagascar: green crystals, some large.
Zillerthal, Austria; Grisons, Switzerland: both gem localities in past years.
Sri Lanka: dark brown, yellowish green, honey yellow.
Pakistan; Burma: some gemmy material found.
Mettur, India: about 30 miles from Salem,Tamilnadu, South India– yellow, brown, green.
Baja, Mexico: yellow-brown, brown, green. dark green (Cr-bearing) gemmy crystals. This may be one of the world’s major sphene deposits, with gemmy crystals to 4 inches.
Minus Gerais, Brazil: twinned yellowish to greenish crystals, often gemmy.
Sphene is also known as “titanite” due to its titanium content. They are yellow, orange, brown or green gems with many gradations between those colors. The usual colors are created by iron and rare-earth element impurities. Sphene is found primarily in Madagascar, Mexico, Canada and, historically, in Austria. Although reasonably available in the marketplace, it is virtually unknown to the general public.
Several gemological characteristics make it beautiful and desirable as a collector’s stone or, with care, for jewelry use. Its dispersion, (fire,) is one of the highest of all gem materials and is higher than diamond. The body color, degree of inclusions, cutting orientation and cutting style may enhance or obscure this feature. If well polished, the luster can approach or equal that of diamond, but the gem is difficult to polish well. The high birefringence usually makes some doubling of facet images visible within the stone giving it a degree of internal fuzziness similar to that often seen in zircon or peridot. A rare variety termed chrome sphene is colored by chromium and is an intense green. Enhancements, imitations or synthetics are not known. This gem is somewhat risky as a jewelry stone due to its softness and brittleness, but beautiful if set protectively and worn occasionally. Shield this gem from knocks, heat and exposure to acids; do not clean with steam or ultrasonics, and it will be a spectacular addition to your gemstone collection or jewelry case.
As is so common in gemstones, color, clarity and size are the most important value factors, followed by the skill and artistry shown in cutting. A preference exists for stones that are lighter in tone, especially yellows, light oranges and greens which are able to best exhibit this gem’s magnificent dispersion. Size is definitely a premium characteristic with this species. Chrome sphene is the most valuable type. In general, specimens with reasonably good clarity, (this stone is rarely even eye clean,) strong and attractive body color and showing at least some dispersion command the best prices.