دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

n: 1. a massive, blocky rock composed of approximately equal proportions of clay and silt, but lacking the fine lamination of shale.2. in general, rock consisting of an indefinite and variable mixture of clay, silt, and sand particles.

sedimentary rocks that consist of particles finer than sand grade (less than 0.0625 mm) and include both silt and clay grade material. Also called shales.