Sapphirine

Sapphirine
(From Sri Lanka. Weight: 0.42 carats total for all 10 stones; 2.1mm round cut.)
Image © supplied by Woodmansee* Gems

Sapphirine History & Etymology:

Sapphirine is a borosilicate mineral. It was given its name because of its sapphire-like color. It was first discovered in 1819.

Sapphirine is considered to be a grandfathered mineral by the IMA. Sapphirine derives its name, as one might expect, from the other precious gemstone sapphire. Though Sapphirine is not related to the precious gemstone sapphire, it is named so because of its blue coloring, which is similar to the coloring of sapphire.

Sapphirine Occurrence:

Sapphirine is extremely rare and are hence found in very few localities across the world. Gemstones quality crystals of Sapphirine are found in only four or five localities in the world. The localities which produce gemstone quality crystals of Sapphirine are Sakena, Anjamiary, Betroka and Bekily regions in Madagascar; Transvaal, Blinkwater and Messina in South Africa, Mautia Hill in Tanzania and Kollone Village in Sri Lanka.

The largest crystals of Sapphirine have been found in Madagascar and South Africa. However the largest crystals of Sapphirine are quite small, measuring just 2 cm in size.

Sapphirine Properties:

Sapphirine is composed of magnesium aluminum silicate. The dominant silicon in the composition of the Sapphirine crystals classifies the crystals as a silicate mineral. Sapphirine is related to the group of Aenigmatite and belongs to the Sapphirine-Surinamite Series.

Sapphirine displays monoclinic and prismatic as well as triclinic and pinocoidal properties. The crystalline masses of Sapphirine occur in their natural form as indistinct crystals in tabular forms which are at least 3 cm in size. The crystalline masses of Sapphirine also occur as aggregates or as a disseminated mass. Twinning in Sapphirine is uncommon. However polysynthetic twinning on one and sometimes two laws is observed. Twinning is also observed in the polished sections where 1A polytype exists.

Cleavages on Sapphirine range from poor to fair along with irregular and sometimes uneven fracturing. The fracturing on Sapphirine can also be of sub conchoidal nature. The fracturing along with cleavages makes the Sapphirine crystals quite brittle. The Moh’s hardness of the Sapphirine crystals is however at 7.5. Sapphirine are relatively dense with a density of approximately 3.5 g/cm3. Sapphirine do not display properties of luminescence nor are they radioactive.

Though Sapphirine derive their name from the precious gemstone sapphire because of the similar blue coloring, Sapphirine are available in various different colors. Sapphirine are available in light blue to dark blue colors as well as bluish gray and sometimes greenish gray colors. Yellow, green, pale red and white colors of Sapphirine crystals also occur but are extremely rare. Sapphirine are usually transparent with little or no inclusions. Sapphirine display a vitreous luster with refractive index varying between 1.7 and 1.73.

Sapphirine occur in metamorphic rocks with high temperature as well as in xenolithic rocks which have abundant supply of magnesium, aluminum and extremely low quantities of silicon. The sapphire like gemstones, Sapphirine is quite sought after by gemstone experts and collectors who pay hundreds of dollars for a single carat.

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