plagioclase
Noun
Meaning
A general term used of any triclinic feldspar. See the Note under Feldspar.
Source: Webster's dictionarySynonyms
Hypernyms
Hyponyms
Examples
Albite is considered both a plagioclase and alkali feldspar.
Note white plagioclase "microlites" in cross-polarized light picture, surrounded by very fine grained volcanic glass.
Feldspar can be divided into two smaller subdivisions: alkali feldspars and plagioclase feldspars.
Gabbro is usually equigranular in texture, although it may be porphyritic at times, especially when plagioclase oikocrysts have grown earlier than the groundmass minerals.
If the sandstone is dominantly plagioclase, then it is igneous in origin.
Intermediate members The intermediate members of the plagioclase group are very similar to each other and normally cannot be distinguished except by their optical properties.