| Text Description: |
From 10' thick flow in the middle of the second andesite package at Site 1 in the Boyden Hills. Fine-grained, vesicular, hypocrystalline, intersertal, intergranular, porphyritic with a matrix of brown glass, clinopyroxene, opaque, minor alteration, microlites and a little plagioclase. Plagioclase phenocrysts (An43-An62) are up to 1.32 mm, and mainly occur as laths that partially include matrix minerals along the rims, some have normal zoning, or occasionally are sieve textured. Olivine phenocrysts are up to 1.5 mm, have some iddingsite alteration, and occasionally have opaque inclusions. Opaque phenocrysts are up to 0.1 mm. |