Ettringite and Polyhalite Physical Properties

Ettringite

Polyhalite

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1 Physical Properties

1.1 Tenacity

Not Available

Brittle

1.2 Solubility

Partially soluble in water

Soluble

1.3 Durability

Not Available

1.4 Specific Gravity

1.772.78

1 7.18

1.5 Fracture

Not Available

Conchoidal, Brittle

1.6 Cleavage

Perfect on {10 1 0}

Perfect on {10 1 }; parting on {010}

1.7 Mohs Hardness

2-2.53.5

2 10

1.8 Chemical Composition

Ca 6Al 2(SO 4) 3(OH) 12 26H 2OMichael OâDonoghue , Gems, Sixth Edition (2006)

Not Available

Ettringite and Polyhalite Chemical Formula

While comparing Ettringite and Polyhalite 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 Ettringite and Polyhalite chemical formula.

Chemical formula of Ettringite- Ca 6Al 2(SO 4) 3(OH) 12 26H 2OMichael OâDonoghue , Gems, Sixth Edition (2006)

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Ettringite and Polyhalite Specific Gravity

Another important criteria for qualitative analysis of gemstones is Ettringite and Polyhalite Specific gravity. Specific gravity is the relative density of a gemstone compared with respect to density of water. Gemologists use Ettringite and Polyhalite Optical Properties during the identification of gemstone. Specific gravity of Ettringite is 2.78 whereas that of Polyhalite is 2.78.