Zircon

1. ppl zircon x20

2. xpl zircon x20

3. ppl w/biotite x20

group                                   orthosilicates
system                                  tetragonal
formula                                 ZrSiO4
optic                                   uniaxial pos
Too-Vee                                 0¡
relief.1                                high pos
min. index                              1.920 / 2.015
color                                   colorless, brown
pleochroism                             yes
birefringence.1                         0.036 - 0.065
cleavage                                no
elongation                              yes
extinction                              parallel
angle                                   0¡
alteration                              not readily altered 
habit.1                                 equant, prismatic, columnar
occurence                               igneous (accessory, mafic), metamorphic (accessory),  sedimentary (clastic, detrital)
TwoV                                    
relief                                  3
pleochroism.2                           brown
birefringence                           9 13
cleavage.2