ppl biotite/musc/chlorite abundant illmenite parallel to foliation with muscovite 10*
ppl biotite/musc/chlorite abundant illmenite parallel to foliation with muscovite 10*
"xpl ""and biotite parallel
ppl good cleavage 5*
xpl strong interference colors 5*
ppl 5*
xpl 5*
1. ppl chlorite N-S x10
2. ppl chlorite E-W x10
3. xpl extinction position x10
4. xpl purple birefringence x10
5. ppl chlorite x10
6. xpl anomolous birefringence x10
group chlorite
system monoclinic
formula (Mg,Fe)5Al(Si3Al)O10(OH)8
optic biaxial neg / pos
Too-Vee 0 - 60¡
relief.1 moderate to high pos
min. index 1.550 / 1.690
color green, colorless, blue
pleochroism yes
birefringence.1 0.000 - 0.015
cleavage yes { cleavage on {001} controls fragment orientation
elongation no
extinction inclined
angle 0 - 9¡ (cleavage)
alteration fairly resistant to alteration, oxidation, clay
habit.1 columnar, tabular, platy
occurence metamorphic (low to medium grade), igneous (hydro- thermal), sedimentary
TwoV 1 2
relief 2 3
pleochroism.2 green
birefringence 1 2 3 4 5 6 7
cleavage.2 {001} perfect, controls fragment orientation