Gneiss is a very general term that refers mainly to a rock texture, rather than a specific rock type. Gneissic texture implies streaking or banding, a lineation in the components of a rock, as opposed to the layering or stratification in sedimentary rocks. Gneiss may therefore be igneous or metamorphic in origin. Gneiss generally contains feldspar, and typically has alternating bands of rounded and flattened mineral grains. The biotite gneiss from Uxbridge, Massachusetts is a good example, where plates of black biotite mica alternate with bands of feldspar and quartz.