It is seen in moonstone and labradorite and is very similar to adularescence and aventurescence. Feldspar phenocrysts typically are labradorite to andesine in composition. Some gemstone varieties of labradorite exhibiting a high degree of labradorescence are called spectrolite. Spectrolite is an uncommon variety of labradorite feldspar. Augite, hypersthene, labradorite, olivine and pyroxene are minerals found in Nemo lavas. The basalt comprises phenocrysts of clinopyroxene and labradorite. Phenocrysts include augite, labradorite, olivine and plagioclase; additionally spinels are found in the rocks. The feldspar variety labradorite is commonly present in anorthosites. Basalt on Lake Island is characterized by abundant to labradorite and clinopyroxene phenocrysts. It commonly occurs in association with orthoclase, sanidine, labradorite, olivine, leucite, amphiboles and other pyroxenes. Labradorite can display an iridescent optical effect (or "schiller") known as labradorescence. The plagioclase ranges from oligoclase to andesine and labradorite. Mineralogically they are essentially formed by labradorite, hornblenda, chlorite Chlorite group and amphibolitized pyroxene. The basic soda-lime feldspars (labradorite to anorthite) are those that undergo this type of alteration. The upper differentiated portions of the intrusion include ilmenite-bearing labradorite anorthosites.