Sillimanite and Blue John Physical Properties

Sillimanite and Blue John Chemical Formula

While comparing Sillimanite and Blue John 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 Blue John chemical formula.

• Chemical formula of Sillimanite- Al 2SiO 5Michael O’Donoghue , Gems, Sixth Edition (2006)
• Chemical formula of Blue John- CaF 2Michael O’Donoghue , Gems, Sixth Edition (2006)

Sillimanite and Blue John Specific Gravity

Another important criteria for qualitative analysis of gemstones is Sillimanite and Blue John Specific gravity. Specific gravity is the relative density of a gemstone compared with respect to density of water. Gemologists use Sillimanite and Blue John Optical Properties during the identification of gemstone. Specific gravity of Sillimanite is 3.00-3.25 whereas that of Blue John is 3.00-3.25.