PLAGIOCLASE

Question 1

plagioclase characteristics

Answer 1

-Colour ranges from white (mainly in more sodium-rich plagioclase) to various shades of grey toward more calcium-rich plagioclase

•colourless fractures in ppl;multiple twinning/compositional zoning in xpl

Question 2

plagioclase occurrence

Answer 2

one of the most common minerals in igneous rocks, and occurs in basic (mafic) to acidic (felsic) rocks. Plagioclase in basic (mafic) rocks is Ca-rich; plagioclase in acid (felsic) rocks is Na-rich