Pigeonite

1. ppl inverted pigeonite x5

2. xpl inverted pigeonite x5

group                                   pyroxene
system                                  monoclinic
formula                                 (Mg,Fe2+,Ca)2Si2O6
optic                                   biaxial pos
Too-Vee                                 0 - 32¡
relief.1                                high pos
min. index                              1.682 / 1.757
color                                   colorless, yellow, green
pleochroism                             yes
birefringence.1                         0.023 - 0.029
cleavage                                yes
elongation                              no
extinction                              parallel, inclined
angle                                   0 - 44¡
alteration                              uralized (altered to fine-grained amphibole)
habit.1                                 prismatic, columnar, tabular
occurence                               igneous (intermediate, mafic), metamorphic
TwoV                                    1
relief                                  3
pleochroism.2                           green, brown, yellow
birefringence                           9 10 11
cleavage.2                              {110} two good cleavages at 87¡