Sphene

1. ppl charac. loqenge shape x10

2. xpl charac. loqenge shape x10

xpl 20*

ppl 20*

group                                   orthosilicates
system                                  monclinic
formula                                 CaTiOSiO4
optic                                   biaxial pos
Too-Vee                                 17 - 40¡
relief.1                                high pos
min. index                              1.843 / 2.110
color                                   brown, colorless, yellow
pleochroism                             yes
birefringence.1                         0.100 - 0.192
cleavage                                yes
elongation                              no
extinction                              inclined, symetrical
angle                                   36 - 51¡
alteration                              Ti-oxides, quartz, leucoxene
habit.1                                 euhedral, subhedral, diamond-shaped
occurence                               igneous (granitic, mafic), metamorphic (medium to high grade, skarn), sedimentary (clastic)
TwoV                                    1
relief                                  3
pleochroism.2                           orange, brown, green
birefringence                           9 13
cleavage.2                              (110) prismatic