1. ppl aenigmatite east-west x5 (I)
group inosilicate
system monoclinic
formula NaFe3+Si2O6
optic sign biaxial neg
2V 60 - 70 degrees
relief high pos
min. index 1.750 / 1.836
color brown, yellow, green
pleochroism yes, green, yellow, brown
birefringence 0.040 - 0.060
cleavage yes, {110} prismatic at about 85 degrees
elongation yes
extinction inclined, symmetrical
extinction angle 0 - 20 degrees
alteration fine-grained amphibole (uralitization) or chlorite
habit prismatic (stubby to elongate), fibrous (finitization)
occurence igneous (alkalic), metamorphic (schist), sedimentary (carbonate)