weighboard

weighboard

(ˈweɪˌbɔːd)
n
(Mining & Quarrying) mining a thin layer (e.g. shale or clay) between bands of thicker strata (e.g. limestone or sandstone)
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014