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tertiary and Cretaceous date. The New Zealand jet usually contains a percentage of water, and, so far, no samples of a bituminous character have as yet been found. There is some uncertainty as to the true nature and origin of jet, as the following article, taken from the " Encyclopaedia Britannica," will indicate : — " Jet, a mineral substance belonging to the Carbonaceous group, and generally regarded as a compact variety of lignite or wood-coal, impregnated with bitumen. The word 'jet' (German Gagat) is a corrupted form of ' Gagates,' the name applied to it, or a similar substance, by Greek and Roman writers;'and derived, according to Pliny (H.N. xxxvi., 34), from the River Gagas in Lycia, where the mineral was originally found. Its occurrence in Britain is mentioned by Solmus, but it was certainly used there in pre-Roman times. Barrows of the bronze age have yielded beads, buttons, rings, and armlets, and other personal ornaments of jet. The early supply was probably obtained from the Yorkshire coast, near Whitby — a locality which still yields the finest varieties. The Whitby jet occurs in isolated masses, of irregular shape, but frequently more or less lenticular, imbedded in bituminous shales near the base of the Upper Lias. The particular horizon of the jet-rock is known to geologists as the zone of Ammonites serpentinus. Opinion is divided as to the exact nature and origin of jet, some regard it as a variety of lignite, others as a kind of cannel coal, and others, again, as a hardened form of bitumen. There is little doubt that the jet has in all cases resulted from the decay of organic matter. Microscopic sections of jet frequently reveal a ligneous structure, in most cases of coniferous type. It has been suggested that masses of wood brought down by a river have been drifted out to sea, where, becoming waterlogged, they have sunk, and have gradually been covered with a deposit of fine black mud, beneath which the decay has slowly proceeded. Possibly bituminous matter may have been distilled from the decaying vegetation and deposited between the layers of shale in its neighbourhood. Drops of liquid bitumen are frequently found in the fossils of the jet-rock, and inflammable gas, derived from bituminous shales, is not uncommon in the jet-mines. Moreover, scales of fish and other fossils of the jet-rock are frequently converted into jet the bituminous matter having replaced the original tissues. When jet is heated it betrays its bituminous character by burning with a dense pungent smoke, which was formerly reputed to possess powerful medicinal virtues. At present the material is used only for trivial ornaments, principally for mourning jewellery. To obtain jet, the shale is systematically mined not only at its outcrop in the cliffs, but in the inland dales of the Cleveland district. It is now rare to find washed jet upon the sea-shore, but formerly a considerable amount was thus obtained. The best hard jet is exceedingly tough, and may be readily carved or turned on the lathe, while its compact texture allows it to receive a high polish. The final polish is given by means of rouge, which produces a beautiful velvety surface. The softer kinds not capable of being freely worked are known as bastard jet. From the estuarine beds of the Lower Oolite of Yorkshire a soft jet is obtained, but, though occasionally used for ornamental purposes, it is far inferior to the true Whitby jet. Spanish let has been largely imported into Whitby, but it is deficient in hardness and lustre. Cannel coal from Scotland is occasionally used in the place of jet; and it is not uncommon for brooches to be made of a carving of Whitby jet set in a plain polished rim of either Spanish jet or cannel. " For descriptions of jet and jet-working, see " The Yorkshire Lias," by Ralph Tate and J. F. Blake, 1876; and a paper on Whitby jet, by J. A. Bower, in the Journal of the Society of Arts, 19th December, 1873."* From the above extract it does appear that jet may originate in a variety of ways, and a variety of substances may eventually be converted to jet. Jet appears at the present time to be regarded as a non-hydrous bituminous substance, under which definition the, Maharahara mineral would have to be excluded; but originally, and as known to Greek and Roman writers, it would seem to have been a Tertiary or Cretaceous mineral, and probably non-bituminous. The formation at Maharahara, ten miles north of Woodville, is of Tertiary-Miocene age, and consists of gravels and sandy clays dipping south-east at high angles, and followed by sandy clays about 100 ft. thick, which are overlain by shelly limestone, constituting a feeble development of the limestones at the upper end of the Manawatu Gorge, and which, as massive beds of shelly limestone, are largely developed to the south-east and east within the Upper Manawatu basin. At Maharahara sandy beds and gravels succeed the limestones, and these in this part of the district close the series of Miocene rocks. The jet-like mineral occurs in connection with the gravels, clays, and sands that underlie the limestone at the distance above stated. The principal masses show a woody structure, and are evidently the trunks and branches of trees that have been covered up by the sandy clays succeeding the gravel-beds. At the same place there is also a thin seam of jet-like coal, which is evidently not buried wood. This, however, is not more than lin. thick, and is of no consequence. The principal mass of jet-coal has been followed about 3ft. into the bank on the south-west side of the road, and on the opposite side of the road a short drive has been put in at a lower level without, however, bringing to light a continuous deposit of the mineral sought for. Pieces of the jet-like coal are found in the bed of the stream next to the south-west, but in this direction it has not been found To the north-east of Maharahara a similar substance is reported as occurring in a seam about 2ft thick but this has merely been observed, and no excavation of the mineral made. Lignite and brown coal are found on the same horizon of the Miocene sequence at several places withm the basin of the Upper Manawatu River and also in the Ruamahunga watershed, near Maunceville, but it is only at Maharahara, and for some distance south-west and north-east, that it assumes the appearance of jet.

• " Encyclopedia Britannica," ninth edition, 1881, Jet.