Perthites
Framework Silicates
triclinic (+,-)
Relief - low
Colour - colourless
RI - 1.518-1.539
Birefringence - 0.006-0.013
Interference colours - 1st order
Extinction - inclined
Comments - exsolution textures of sodic plagioclase in a K-feldspar host (the reverse are antiperthites)
Perthite with crystals of plagioclase
XPL
Perthite
XPL
Perthite, blebs are of albite-twinned plagioclase
XPL
Carlsbad-twinned perthite
XPL