Gabbro. Polarised light micrograph of a thin section of gabbro, an igneous rock. Gabbro is coarsegrained, containing the minerals olivine and plagioclase feldspar. Olivine is recognised here by its irregular shaped crystals, with randomly oriented fractures. Plagioclase feldspar forms lath shaped crystals. Specimen of rock obtained from the Bushveld range in the Transvaal, South Africa. Magnification: x8 at 6x7cm size.
