| Text Description: |
Block from an about 36' thick block and ash flow at Site 3. Fine-grained, seriate to porphyritic, intersertal, intergranular, hypocrystalline with a matrix of brown glass, opaque, clinopyroxene, feldspar and a little greenish alteration. Plagioclase phenocrysts (An45-An53) are up to 2.05 mm and have complex and convolute zoning; some grains have been resorbed and then overgrown, while others have resorption embayments; a second population is 0.2-0.5 mm, lath shaped and lack zonation. Clinopyroxene phenocrysts are up to 0.15 mm. A entirely altered phase, olivine?, is 0.1-0.6 mm. Mode: 85.9% matrix, 12.4% plagioclase, 1.6% altered phase, 0.1% vesicles. |