| Text Description: |
A 5-6’ thick dike, trending N90°E, with columnar jointing. Along the edge of the dike there is vitrophyre that is probably remelted host material. Fine grained, hypocrystalline, intersertal, porphyritic with a matrix of brown glass, opaque, plagioclase, green alteration patches, clinopyroxene and calcite patches. Plagioclase phenocrysts (An32 - An64) are up to 2.25 mm and many have sieve textured cores with overgrowth rims, some have oscillatory zoning, and a few have resorption embayments. Olivine phenocrysts are up to 0.9 mm and most are altered leaving only a few olivine cores. Orthopyroxene phenocrysts are up to 0.5 mm and have clinopyroxene rims. Opaque phenocrysts are up to 0.1 mm. |