views updated

poikilitic Applied to the texture produced when several orientated or unorientated crystals are enclosed within a larger crystal in an igneous rock. The larger crystals have more widely separated nuclei than the enclosed crystals, and may grow faster, thus enclosing surrounding grains. Where augite encloses a number of plagioclase feldspar crystals the poikilitic texture is given the specific name of ‘ophitic texture’.