Lapis lazuli and Alexandrite Physical Properties

Lapis lazuli

Alexandrite

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1 Physical Properties

1.1 Tenacity

Not Available

1.2 Solubility

Not Available

1.3 Durability

Not Available

1.4 Specific Gravity

2.50-3.00

3.69-3.81

1.5 Fracture

Uneven-Conchoidal, ConchoidalWalter Schumann, Gemstones of the world (2001)

Not Available

1.6 Cleavage

3,6

1,1 ; 3,2.

1.7 Mohs Hardness

5.5

8.5

1.8 Chemical Composition

The chief constituent Lapis Lazuli is Lazurite, with the following chemical formula: (Na,Ca)₈Al₆Si₆O₂₄(S,SO)₄

BeAl ₂ O ₄

Lapis lazuli and Alexandrite Chemical Formula

While comparing Lapis lazuli 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 Lapis lazuli and Alexandrite chemical formula.

Chemical formula of Lapis lazuli- The chief constituent Lapis Lazuli is Lazurite, with the following chemical formula: (Na,Ca)₈Al₆Si₆O₂₄(S,SO)₄
Chemical formula of Alexandrite- BeAl ₂ O ₄

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Lapis lazuli and Alexandrite Specific Gravity

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