Some peridotites appear low down in ophiolite complexes, layered along with pyroxenite. Others seem to accumulate at the bottom of gabbro intrusions when olivines crystallize and settle out. A few peridotites are squeezed upwards in deep volcanic pipes. Rare chunks of peridotite reach the surface as solid lumps, swept up as xenoliths in liquid magma - spinel peridotites in basalt, basanite, nephelinite and occasionally andesite, and garnet peridotites in kimberlites and lamproites.