| Text Description: |
A juvenile block from the lahar/pyroclastic flow immediately overlying silicic material from Dome A and underlying flows and agglutinate of unit nA1 at Site 5. Fine-grained, hypocrystalline, intersertal, locally intergranular, seriate porphyritic with a matrix of brown glass, opaque and feldspar microlites. Plagioclase phenocrysts (An28 - An58) are up to 1.75 mm and some have sieve textured cores and/or intermediate zones, complex zoning, and rarely have resorption embayments and/or tooth-like overgrowth rims. Orthopyroxene phenocrysts are up to 1.0 mm and have clinopyroxene rims with occasional sieve textured zones; some anhedral orthopyroxene is intergrown with plagioclase. Clinopyroxene phenocrysts are up to 0.2 mm |