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Goethite
Goethite

Opal
Opal



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Goethite
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Opal

Goethite and Opal Physical Properties

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Physical Properties

Tenacity

-
BrittleWalter Schumann

Solubility

HCl soluble
hot salt water

Durability

-
-

Specific Gravity

4.27-4.291.98-2.25
1 7.18
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Fracture

Uneven
Conchoidal

Cleavage

Perfect {010}
None

Mohs Hardness

5-5.55-6.5
2 10
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Chemical Composition

FeO(OH)Arthur Thomas , Gemstones (2009)
SiO2 · nH2O

Goethite and Opal Chemical Formula

While comparing Goethite and Opal 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 Goethite and Opal chemical formula.

  • Chemical formula of Goethite- FeO(OH)Arthur Thomas , Gemstones (2009)
  • Chemical formula of Opal- SiO2 · nH2O

Goethite and Opal Specific Gravity

Another important criteria for qualitative analysis of gemstones is Goethite and Opal Specific gravity. Specific gravity is the relative density of a gemstone compared with respect to density of water. Gemologists use Goethite and Opal Optical Properties during the identification of gemstone. Specific gravity of Goethite is 1.98-2.25 whereas that of Opal is 1.98-2.25.