11. Tephrite is foidal basalt with essential calic plagioclase but without essential olivine. 12. Anorthosites form in plutons and are composed mostly of plagioclase . 13. The plagioclase phenocrysts occasionally reach a grain-size of 10 millimeters. 14. At the top left is a distinct phenocryst of plagioclase . ]] 15. Argillic assemblages include kaolinite replacing plagioclase and montmorillonite replacing amphibole and plagioclase. 16. Argillic assemblages include kaolinite replacing plagioclase and montmorillonite replacing amphibole and plagioclase . 17. The rhyodacite is characterized by phenocrysts of plagioclase , quartz and biotite. 18. Strongly-zoned plagioclase with sieve texture also occurs in those rocks. 19. Plagioclase is the main component of most lavas, with subordinate clinopyroxene.20. It contains biotite, orthopyroxene, plagioclase and smaller amounts of quartz.
