Corundum and Sillimanite Physical Properties

Corundum

Sillimanite

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1 Physical Properties

1.1 Tenacity

Brittle

Tough

1.2 Solubility

insoluble

Not Available

1.3 Durability

Not Available

1.4 Specific Gravity

3.90-4.053.20-3.26

1 7.18

1.5 Fracture

Uneven, Uneven, Gems, Difficult, Fibrous

Splintery

1.6 Cleavage

None – parting in 3 directions

{010} perfect

1.7 Mohs Hardness

96-7.5

2 10

1.8 Chemical Composition

Al 2O 3Arthur Thomas , Gemstones (2009)

Al 2SiO 5Michael OâDonoghue , Gems, Sixth Edition (2006)

Corundum and Sillimanite Chemical Formula

While comparing Corundum and Sillimanite 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 Corundum and Sillimanite chemical formula.

Chemical formula of Corundum- Al 2O 3Arthur Thomas , Gemstones (2009)
Chemical formula of Sillimanite- Al 2SiO 5Michael OâDonoghue , Gems, Sixth Edition (2006)

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Corundum and Sillimanite Specific Gravity

Another important criteria for qualitative analysis of gemstones is Corundum and Sillimanite Specific gravity. Specific gravity is the relative density of a gemstone compared with respect to density of water. Gemologists use Corundum and Sillimanite Optical Properties during the identification of gemstone. Specific gravity of Corundum is 3.20-3.26 whereas that of Sillimanite is 3.20-3.26.