Muscovite

Muscovite

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1. ppl relief and cleavage x10

2. xpl relief; cleavage; max bir x10

3. xpl parallel extinction x10

ppl 10*

xpl 10*

ppl 10*

group                                   mica
system                                  monoclinic
formula                                 KAl2(AlSi3O10)(OH)2
optic                                   biaxial neg
Too-Vee                                 30 - 47
relief.1                                moderate pos
min. index                              1.552 / 1.623
color                                   colorless, pink, green
pleochroism                             no
birefringence.1                         0.036 - 0.049
cleavage                                yes
elongation                              yes
extinction                              parallel
angle                                   0 - 3
alteration                              not readily altered, clay minerals (sericite)
habit.1                                 columnar,  tabular
occurence                               igneous (felsic), metamorphic (low to meduim grade, regional, pelite),  hydrothermal
TwoV                                    1
relief                                  2
pleochroism.2                           
birefringence                           9 13
cleavage.2                              {001} perfect, controls fragment orientation