Magnetite

1. ppl magnetite x20

2. ppl symplecite x10

3. xpl symplecite x10

group                                   spinel
system                                  isometric
formula                                 FeFe2O4
optic                                   opaque
Too-Vee                                 0¡
relief.1                                ***
min. index                              ***
color                                   opaque
pleochroism                             no
birefringence.1                         no
cleavage                                no
elongation                              no
extinction                              no
angle                                   0¡
alteration                              hematite, limonite, goethite, lamellae of illmenite
habit.1                                 equant, anhedral, granular
occurence                               igneous (accessory), metamorphic (skarn), sedimentary
TwoV                                    
relief                                  
pleochroism.2                           
birefringence                           
cleavage.2                              ( {111} parting but not visible)