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Sphene (Titanite): description, properties and photo
Sphene (Titanite)
Sphene (titanite) is one of the main ore minerals containing titanium. Samples of gem quality are very rare and can be compared with diamonds in the play of light. The mineral was named for the characteristic shape of the crystals, because from ancient greek “sphenos” means “wedge”. The second common name for this stone is titanite. The mineral is found in the form of single flattened crystals of a wedge-shaped shape and twin splices. Occasionally forms needle and granular aggregates. It is transparent or translucent. It also has a high birefringence of light.
Titanite color is diverse and depends of it chemistry content. The iron content gives yellow, green or brown. The most valuable color is bright green, which is due to the chromium content. Colorless samples are occasionally mined. For brightly colored stones, the presence of a strong dichroism property is characteristic. Titanites require careful wearing in jewelry and gentle care, as they have not too high hardness. In view of the rarity of large samples of gem quality, titanites are attractive objects for collecting.
Among the valuable properties of the mineral, the most attractive for gem lovers is the high dispersion (0.051), which creates rainbow flashes on the edges when a ray of light hits. Note the birefringence, which is actually the difference between the maximum and minimum refractive index of the sample, a consequence of anisotropy, which also manifests itself as observed in some cases, bifurcation of edges when viewed through a stone. Diamond luster, another valuable property, contributes to the excellent play of faceted titanite.
DEPOSITS
Gem quality sphene is quite rare. The main sources are: Madagascar, Pakistan, Tajikistan, Sri Lanka, Myanmar (Burma), Brazil and the USA. Most gem quality stones in the world market are stones from Madagascar.
Properties
Mineral:
sphene (titanite)
Chemical formula:
CaTiSiO5
Crystal Systems:
monoclinic
Mohs scale hardness:
5-5.5
Optical character:
anisotropic
Cleavage:
medium in two directions
Density:
3.50-3.54 g/cm3
Lustre:
Subadamantine
Refractive index:
1,900-2,034 (± 0,020)
Birefringence:
0.100-0.135
Dispersion:
0.051
Color:
yellow, green, orange, brown, red
Interesting facts
The dispersion of sphene is superior to the dispersion of diamond.
Most faceted specimens do not exceed 4 carats by weight.
Gem quality stones began to enter the world market only after the discovery of new deposits in 2004.
History
In ancient Egypt the mineral was endowed with magical properties. The Egyptians adorned their sacred animals - cats, with collars, into which spheres were inserted, so that they would protect them from any misfortunes. This stone was also used as an amulet by priests in the sacred temple of the god Ra, the god of the sun. He sparkled brightly in the rays of sunlight, which seemed to show that he was keeping a piece of the sun god Ra.
Enhancement
Sphene is very rarely subjected to treatment. However, it is known that by heat treatment it is possible to lighten its dark color.
Photo
In the photo: yellow gemstone weighted 9.93 ct with high clarity and excellent cutting
Two large sphenes (25.17 and 22.18 ct) with different shades
Orange garnet spessartite: description, properties and photo
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