KENDALL, Hugh P.
The Story Of Whitby Jet (1936)
its workers from earliest times
Republished by Whitby Literary and Philosophical Society, Whitby, 1977
Brochure op geglaceerd papier, 26 blz., geniet, geïllustreerd met zwart/wit foto's
Scientific investigation in recent years has finally established the fact that jet is really driftwood, which has been subject to chemical action in stagnant water, and afterwards flattened by enormous pressure. The jet rock is a lias shale, dark blue to black in colour, dense in texture, and smelling strongly of oil when freshly broken. Its position in the geological strata of the coast is below the bituminous and alum shales of the lias rock, the lias consisting of the solidified mud of an ancient sea which once existed over what is now Cleveland. The hardest and best variety of jet is found only in the lower bed of the Upper Lias, whilst a softer quality is found in the upper part of the Upper Lias, but this will not stand atmospheric conditions like the harder jet, which has a conchoidal fracture, and is highly electric under friction.