37+ Oligoclase Thin Section Gif. In chemical composition and in its crystallographic and physical characters it is intermediate between albite (naalsi3o8) and anorthite (caal2si2o8). Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continuous solid solution series.
Plagioclase is not amongst the most valuable ore types around, but it has the largest amount of pyerite of any ore and is thus always in constant demand. Quartz, orthoclase, and oligoclase generally vary directly with each other and so are plotted. Oligoclase thin section under microscope.
It also yields some tritanium and mexallon.
The zoning in plagioclase feldspars is zoned as the magma body changes composition. How are thin sections made? Perthite refers to rocks characterized by the intergrow mesoperthite. In thin section the plagioclase crystals show a distinctive cream coloured clouding, probably due to oriented inclusions of spinel (poldervaart and gilkey, 1954).