Fissility or fissibility refers to the property of rocks to split along planes of weakness into thin sheets. This is commonly observed in shales, which are sedimentary rocks, and in slates and phyllites, which are foliated metamorphic rocks. The fissility in these rocks is caused by the preferred alignment of platy phyllosilicate grains due to compaction, deformation or new mineral growth. A highly fissile rock splits easily along the cleavage.
- Tucker , M.E. 2001. Sedimentary petrology: an introduction to the origin of sedimentary rocks, WileyBlackwell, 3rd Edition, 272pp.
- Ingram, R.L. 1953. Fissility of mudrocks, GSA Bulletin, 64, 869-878.
- Chattanooga Shale: The shale is highly fissile (easily cleaved) most often black but may be brown where weathered. Anderson, Carl (1976) "Index and Short Description to the Geologic terms used by the GSS" Georgia State Base Geologic Map page 5; archived Archived July 3, 2011, at the Wayback Machine. by Internet Archive on 3 July 2011