Taafeite Value, Price, and Jewelry Information

Optics: o= 1.721-1.724; e = 1.717—1.720.

Uniaxial. (-).

Zincian: o= 1.730; e= 1.726; birefringence = 0.004.

Inclusions: Inclusions reported in Sri Lankan taaffeites include: phlogopite; garnet; muscovite; apatite; spinel; zircon; fingerprints of negative crystals and spinels; and partly healed liquid fractures. The apatite crystals tend to be well-formed prisms, colorless to yellow. The apatites, negative crystals, and fingerprints are commonly observed.

Occurrence: In metamorphosed limestones and skarns; also as rolled pebbles, very rarely (China) in crystals (microscopic).

China: reported in dolomitized limestone in Hunan Province (o= 1.720; e=1.741; birefringence = 0.006).

Burma: (o= 1.720; e= 1.716; birefringence=0.004; S.G. = 3.59).

USSR: (o= 1.735; e= 1.726; birefringence =0.009).

Sri Lanka: assumed origin of most known cut gems.

Note: Polytype of taaffeite discovered in the Musgrave Ranges, Central Australia (o= 1.739: e= 1.735; S.G. =3.68).

Comments: Taaffeite reacts to most gemological tests like mauve-colored spinel, but can be distinguished on the basis of its birefringence. Additional stones will undoubtedly be discovered in the future (generally misidentified as spinel) as collectors search for these rarities. Taaffeite is one of the rarest of mineral species, and surely among the very rarest and most desirable of all collector gemstones.

A zincian taaffeite With ZnO as high as 4.66% has been reported. The material is reddish violet due to Mn and Cr and has higher refractive indices and S.G. than normal taaffeite. A red gemstone (1.02 carats) was reported from Sri Lanka with the following properties: R.l. = 1.717—1.721, birefringence =0.004, S.G. =3.61, hardness= 8+, hexagonal, slight reddish luminescence, Cr presents (emission line in spectrum). This was first thought to be taaffeite, later considered a new species and named taprobanite (after Taprobane, ancient name of the island of Sri Lanka). This material was eventually proven to be a taaffeite after all, and the name taprobanite has been dropped from use. However, the intense research into this problem led to a revised formula for taaffeite.

Name: After Count Taaffe, Bohemian-Irish gemologist, who discovered the first stone in 1945.