Petedunnite

Petedunnite is a very rare mineral that is a member of the Pyroxene Group of minerals that includes Aegirine, Diopside, Hedenbergite, Hypersthene, Jadeite, Petedunnite and Spodumene. The chemical formula of Petedunnite is Ca(Zn, Mn2+, Fe2+, Mg)Si2O6 (Calcium Zinc Manganese Iron Magnesium Silicate) and its molecular weight is 246.86 gm. Petedunnite has a specific  gravity of 3.68 (g/cm3) and the refractive index 1.68 – 1.70 Biaxial ( + ). Petedunnite is only available from one source: Franklin, Franklin Mining District, Sussex County, New Jersey, USA. It is found as anhedral grains; granular without the expression of crystal shapes and containing abundant inclusions. 

Chemical Formula: Ca(Zn,Mn2+,Fe2+,Mg)Si2O6  
Calcium Zinc Manganese Iron Magnesium Silicate
Molecular Weight: 246.86 gm
Composition: 
Sodium 0.93 % Na 1.29 % Na2O
Calcium 14.61 % Ca 20.44 % CaO
Magnesium 0.98 % Mg 1.63 % MgO
Manganese 4.45 % Mn 5.75 % MnO
Zinc 10.60 % Zn 13.19 % ZnO
Iron 6.79 % Fe 5.82 % FeO  /  3.23 %   Fe2O3
Silicon 22.75 % Si 48.68 % SiO2
Oxygen 38.89 % O
  100.00 % 100.00 % = TOTAL OXIDE
 

 

Cleavage: [110] Distinct/Good
Fracture: Irregular/Uneven, Conchoidal
Tenacity: Brittle
Moh’s Hardness: 5.0 – 6.0
Density: 3.68 (g/cm3)
Luminescence: None
Radioactivity: Not Radioactive

 

 

Color: Dark green; in transmitted light, light Yellow to pale Green
Transparency: Translucent
Luster: Vitreous
Refractive Index: 1.68 – 1.70  Biaxial ( + )
Birefringence: 0.0200
Dispersion: Strong; r > v
Pleochroism: X = Y = light yellow; Z = light gree