Sample SP57 Olivine Gabbro

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Olivine Gabbro. This rock is holocrystalline, phaneritic, fine- to medium- grained, hypidiomorphic seriate. All crystals are subhedral except olivine and opaque minerals (<1 mm) which are subhedral to anhedral. The following are present as phenocryst phases: olivine (.5-2 mm) is moderately altered to iddingsite; biotite (.5-2 mm); orthopyroxene and titanaugite (both <1 mm) are present with the latter exhibiting one or more of oscillatory zonation, hourglass zonation, and sieve texture; plagioclase (1 mm); spherulitic potassium feldspars (1 mm); analcite (<1 mm); zircon (<1 mm); apatite (<1 mm); chlorite (<1 mm). Red-brown, anhdedral, pleochroic phlogopite grades, in places, into biotite.