The arenaceous rocks (arenites) include all those clastic sedimentary rocks whose particle sizes range from 2 to 0.06 mm, or if silt is included, to 0.004 mm. Some arenites are composed primarily of carbonate particles, in which case they are called calcarenites and grouped with the limestones. Some oolitic iron ores and glauconite beds are properly classified as arenites. But the vast majority of arenites are commonly called sandstones, and the two words are almost synonymous.