| Text Description: |
At least 50’ thick, columnar jointed flow with classic colonnade and entablature at south end of Jaeger Mesa. Fine grained, hypocrystalline, porphyritic to glomeroporphyritic with a matrix of pale brown glass, opaque, plagioclase, clinopyroxene and orthopyroxene. Plagioclase phenocrysts (An42 - An52) are up to 3.37 mm and tend to have normal zoning, large melt inclusions, and occasional resorbed rims. Orthopyroxene phenocrysts are up to 1.5 mm, but most are <0.4 mm. Clinopyroxene phenocrysts are up to 0.35 mm. Olivine phenocrysts are up to 0.2 mm. |