11. Their matrix is heavily altered to clay while phenocrysts are mostly preserved. 12. The rocks contain phenocrysts of clinopyroxene, hornblende and plagioclase. 13. Feldspar phenocrysts typically are labradorite to andesine in composition. 14. Sanidine phenocrysts and augite ( or enstatite ) are found in some samples. 15. Basalt on Lake Island is characterized by abundant to labradorite and clinopyroxene phenocrysts . 16. Mineralogically the fine-grained phenocrysts consist of quartz, feldspars and biotite. 17. Plagioclase and, in lesser measure, clinopyroxene and olivine form its phenocrysts . 18. The andesitic lavas contain phenocrysts of andesine, hornblende, plagioclase and hypersthene. 19. It contains microcline, and few feldspar phenocrysts . 20. The distinctive texture of rapakivi granite is due to oligoclase rims on orthoclase phenocrysts .
