a white or grayish variety of plagioclase, CaAlSiO, found in basic igneous rocks
Origin of anorthite; from Classical Greek an-, not + orthos, straight (see ortho-) + -ite
A white to gray variety of plagioclase feldspar that contains a high proportion of calcium to sodium and occurs in alkaline igneous rocks such as gabbro and anorthosite.
Origin of anorthiteFrom Greek an-, not; see a–1 + orthos, straight (from its oblique crystals).
- (mineralogy) A plagioclase feldspar, the final member of the Albite-Anorthite solid solution series. Anorthite is very rare on Earth, but abundant in moon rocks. This is because Anorthite weathers rapidly to clay minerals under atmospheric conditions. Good crystals have been found in lava-digested limestone blocks erupted from Mount Vesuvius.
- Physical properties:
From Ancient Greek "less than straight, not perpendicular" - a reference to the odd angles at which crystals grow.