A screen, often of wood and including a crucifix, that separates the nave from the sanctuary portion of a church. Field stones are often used for rubble. A rock consisting primarily of serpentine. Chert, jasper, and quartz are made of silica. A rock derived from the metamorphism of shale.
Slate is harder and more durable than shale, but breaks easily into thin layers.
Limestone is easily dissolved by weak acids. The dark color of stylolites is due to a concentration of insoluble materials that remained behind. A baked clay used to make tiles, panels for building facing, and statuary. Flooring composed of stone chips set in a cement matrix. A footprint, trackway, burrow, or other indirect evidence of a prehistoric animal.