[sheyl] 
| a rock of fissile or laminated structure formed by the consolidation of clay or argillaceous material. |
| shale (shāl) n. A fissile rock composed of layers of claylike, fine-grained sediments. [Probably from Middle English, shell, from Old English scealu; see skel-1 in Indo-European roots.] shal'ey adj. |
| shale (shāl) Pronunciation Key
A fine-grained sedimentary rock consisting of compacted and hardened clay, silt, or mud. Shale forms in many distinct layers and splits easily into thin sheets or slabs. It varies in color from black or gray to brown or red. |