Mid-infrared (2.5 to 13.5 mm) spectra of igneous rocks

Abstract

Hand Sample Description: The sample is about 4x3 cm, brown on the weathered surface and dark gray on fresh surfaces. It is porphyritic with the phenocrysts making up about 25-30% of the rock. The groundmass is gray and microcrystalline. The phenocrysts are ~< 1mm and consist of plagioclase laths, pyroxene and opaques, in that order of abundance, with pyroxenes nearly as abundant as the feldspars.