NJDEP - NJGS - First Annual Report of the Geological Survey of the ...

18stream of water, and determining its depd,, capacity, &e.; butin regard to the correctness of his statements I had no visibleevidence.One of the most eqmmon delusions, and one that has caused.a great expenditure of money, is the flashing of lights andrumbling noises, concerning which many notions are entertained.Daring the past summer, I found men on the Blue.Mountain digging for gold in the hard Shawangunk grit,where lights were said to have been seen ; and numerous arethe excavations that have been made there in search of gold,solely on-account of.some traditionary tale about the appcaranneof fire or smoke. Among the inhabitants of that mountainthere is hardly a man who has not heard of lights andrumbling noises. In several of the excavations I found ironpyrites, which, by a rapid decomposition, sometimes producesa great deal of heat and even smoke ; and if lights have everbeen seen, their origin can be referred to the pyrites. Fo_the information of those who are so credulous in such matters,I may l_e allowed to say that they are no indication of valuablemineral deposits.The occurrence of iron pyrites, to a greater or less extent,in almost all the rocks of the northern part of the State, hasbeen the cause of a useless _xpenditure of money. On accountof its resemblanea to gold in color, and the frequencyof its being mistaken for that mineral, it has been called"fool's gold?' Many have sought me with parcels of it carefullywrapped in paper_which they had obtained at an expenditureof much labor and money, and have asked its value,together with advice as to the best method of continuing theirwork. It may be readily distinguished from gold by holdihgit in the flame of a candle or throwing it in the tire, when itwill lose its b_'illiant hue; while gold, under the same circumstances,will preserve its color. It may also be detected byits brittleness ; for if the point of a knife be pressed againstit, it will break readily, while gold is tenacious and difficult tobe .broken. . .The frequent occurrence of dark-colored slates and shalesNEW JERSEY GEOLOGICAL SURVEY