Page:The Journal of geology (IA journalofgeology11893univers).pdf/186

The recent closing down of the silver mines of Colorado and other Western states means not only a lessening of the silver production of the country, but also the shutting off of its greatest source of lead supply. During the past few years over two-thirds of the total yield of domestic lead has been from the argentiferous lead ores of Colorado, Utah, Idaho, Montana and Nevada. Unless operations are resumed in the West, the demand must consequently soon be concentrated upon the deposits of non-argentiferous lead in the Mississippi Valley, which have been in the past the sole important producers. A rise in the price of lead is to be expected as a result, which, in turn, will lead to increase in exploitation and development.

The question naturally arises, therefore, to what extent are these Mississippi Valley deposits to be depended upon for future supply. They have been large and almost constant producers in the past; will they continue to be such in the future? The history of their development, which is in many respects remarkable, lends color to the hope that such will be the case, especially in Missouri. Lead mining was begun in that state as much as 170 years ago, and has continued almost uninterruptedly since. Indeed, the first deposit worked, that of Mine La Motte, has up to this year supplied large quantities of ore, the total value of its product to date being the neighborhood of $8,000,000. The various bodies of ore have shown signs of exhaustion from time to time, and the industry in the state has waned. About the year 1854 the condition was such that even so competent a judge as Prof. J. D. Whitney^[1] ventured the prediction that the supply was nearly exhausted, and that the lead mining of Missouri was a thing of the past. But ever after such depression, deeper excavations have developed new bodies of untouched ores, wider explo-