A housing for a mine marker that houses RFID electronics. The RFID electronics is surrounded by a resiliently deformable tube that fits inside the housing, which may be an impact resistant plastic. The housing is filled with a first strengthening material and the tube may be filled with a second strengthening material. There is an impedance mismatch (a change in properties between adjacent layers so that shock waves are deflected) at the boundary between adjacent materials, (casing and first strengthening material, first strengthening material and tube, tube and second strengthening material, or casing and tube if they abut) which inhibits shock propagation.