Biotite and Cordierite Physical Properties
Tenacity
Brittle
  
Brittle
  
Solubility
Not Available
  
Not Available
  
Durability
Not Available
  
Not Available
  
Specific Gravity
2.7-3.3
  
2.57-2.66
  
Fracture
Uneven, Even, Yellow, White
  
Subconchoidal, Conchoidal, Brittle
  
Cleavage
Perfect on the {001}
  
Fair on {100}, poor on {001} and {010}
  
Mohs Hardness
2.5-3.0
  
7-7.5
  
Chemical Composition
K(Mg,Fe++)3[AlSi3O10(OH,F)2
  
Mg2Al4Si5O18
  
Biotite and Cordierite Chemical Formula
While comparing Biotite and Cordierite 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 Biotite and Cordierite chemical formula.
- Chemical formula of Biotite- K(Mg,Fe++)3[AlSi3O10(OH,F)2
- Chemical formula of Cordierite- Mg2Al4Si5O18
Biotite and Cordierite Specific Gravity
Another important criteria for qualitative analysis of gemstones is Biotite and Cordierite Specific gravity. Specific gravity is the relative density of a gemstone compared with respect to density of water. Gemologists use Biotite and Cordierite Optical Properties during the identification of gemstone. Specific gravity of Biotite is 2.57-2.66 whereas that of Cordierite is 2.57-2.66.