Which one of the following is a sodium and calcium feldspar with twinning striations?
A) sanidine
B) microcline
C) orthoclase
D) plagioclase

Question

Quizplus · Accepted Answer

Plagioclase is a series of tectosilicate minerals within the feldspar group that consists of a continuous solid solution series from albite (sodium) to anorthite (calcium). It is characterized by its twinning striations, which are a distinctive feature used in its identification.

Which One of the Following Is a Sodium and Calcium