Chloritoid

ppl 5*

xpl 5*

ppl min. pleochroism N-S 5*

ppl max. pleochroism E-W 5*

xpl max. birefringence 10*

xpl 10*

ppl 10*

group                                   orthosilicate
system                                  monoclinic
formula                                 see  properties
optic                                   biaxial pos
Too-Vee                                 36 - 72¡
relief.1                                high pos
min. index                              1.705 / 1.740
color                                   green
pleochroism                             yes
birefringence.1                         0.005 - 0.022
cleavage                                yes
elongation                              yes
extinction                              inclined 
angle                                   10 - 25¡
alteration                              chlorite, sericite
habit.1                                 lathlike, tabular
occurence                               metamorphic (low to medium grade, regional), hydrothermal
TwoV                                    1 2
relief                                  3
pleochroism.2                           green, blue, yellow
birefringence                           1 2 3 4 5 6 7 8
cleavage.2                              {001} perfect, {110} two imperfect