Monoclinic

Ca - Mg - Fe2+

Hornblende K(Ca,Na,K)2-3(Mg,Fe2+,Fe3+,Al,Ti)5[(OH,F)/(Al,Si)Si3O11]2

Hornblende 1P
 Colour: green, brown
Pleochroism: pleochroic
Habit: prismatic, commonly cross sections are 6 sided
Relief: positive
Cleavage, fracture: in horizontal section - good, single cleavage, in cross sections - good, double cleavage at 124º
Hornblende PX
 Isotropic or anisotropic: anisotropic
Extinction: inclined
Interference colours: 1st/2nd order

Lamprobolite K(Ca,Na,K)2-3(Mg,Fe2+,Fe3+,Al,Ti)5[(O,OH,F)/(Al,Si)Si3O11]2

Lamprobolite 1P
 Colour: red, brown
Pleochroism: pleochroic
Habit: prismatic, cross sections are 6 sided
Relief: positive
Cleavage, fracture: in horizontal section - good, single cleavage, in cross sections - good, double cleavage at 124º
Lamprobolite PX
 Isotropic or anisotropic: anisotropic
Extinction: inclined
Interference colours: 1st/2nd order
Last modified: Monday, 3 April 2017, 10:51 AM