Grossular

ppl 20*

xpl 20*

group                                   garnet
system                                  isometric
formula                                 Ca3Al2(SiO4)3
optic                                   uniaxial / biaxial
Too-Vee                                 0 - 90¡
relief.1                                high pos
min. index                              1.735 / 1.770
color                                   colorless
pleochroism                             no
birefringence.1                         anomalous
cleavage                                no
elongation                              no
extinction                              ***
angle                                   ***
alteration                              chlorite, hornblende, epidote, and iron oxides
habit.1                                 equant , euhedral
occurence                               metamorphic (carbonate,skarn)
TwoV                                    1 2
relief                                  3
pleochroism.2                           
birefringence                           
cleavage.2