Corundum and Alexandrite Physical Properties

Corundum

Alexandrite

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1 Physical Properties

1.1 Tenacity

Brittle

Not Available

1.2 Solubility

insoluble

Not Available

1.3 Durability

Not Available

1.4 Specific Gravity

3.90-4.053.69-3.81

1 7.18

1.5 Fracture

Uneven, Uneven, Gems, Difficult, Fibrous

Not Available

1.6 Cleavage

None – parting in 3 directions

1,1 ; 3,2.

1.7 Mohs Hardness

98.5

2 10

1.8 Chemical Composition

Al 2O 3Arthur Thomas , Gemstones (2009)

BeAl ₂ O ₄

Corundum and Alexandrite Chemical Formula

While comparing Corundum and Alexandrite 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 Alexandrite chemical formula.

Chemical formula of Corundum- Al 2O 3Arthur Thomas , Gemstones (2009)
Chemical formula of Alexandrite- BeAl ₂ O ₄

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Corundum and Alexandrite Specific Gravity

Another important criteria for qualitative analysis of gemstones is Corundum and Alexandrite Specific gravity. Specific gravity is the relative density of a gemstone compared with respect to density of water. Gemologists use Corundum and Alexandrite Optical Properties during the identification of gemstone. Specific gravity of Corundum is 3.69-3.81 whereas that of Alexandrite is 3.69-3.81.