SPI Supplies Individual Microanalysis Standard Item, Minerals Group, Plagioclase

This is a reflected light micrograph of polished, carbon coated plagioclase felspar crystals. The identifying etched label, which is a feature of our standards, is invaluable for navigating in an electron beam instrument. Felspars are the most abundant group of silicate minerals with compositions ranging from potassium to sodium to calcium rich end members. The plagioclases range from sodium rich (albite - AS501 in this collection) to calcium rich (anorthite). This example is a labradorite with 62% of the anorthite end member and is therefore a most useful standard for general silicate work.