Sillimanite and Allanite Physical Properties

Sillimanite and Allanite Chemical Formula

While comparing Sillimanite and Allanite physical properties, the important data you should know is its chemical composition. Since chemical formula defines the molecular structure of the crystal, most of the physical properties like color, tenacity, solubility are governed by Sillimanite and Allanite chemical formula.

• Chemical formula of Sillimanite- Al 2SiO 5Michael O’Donoghue , Gems, Sixth Edition (2006)
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Sillimanite and Allanite Specific Gravity

Another important criteria for qualitative analysis of gemstones is Sillimanite and Allanite Specific gravity. Specific gravity is the relative density of a gemstone compared with respect to density of water. Gemologists use Sillimanite and Allanite Optical Properties during the identification of gemstone. Specific gravity of Sillimanite is 3.40-4.20 whereas that of Allanite is 3.40-4.20.