The composition and origin of the rock dolomite

Abstract

This paper considers briefly the question of the origin of the rock dolomite, which has long been regarded as a standing enigma in our science. In order to deal with the subject in as concise a manner as possible, I will first give—from my stand-point, of course—a brief account of the composition, mode of occurrence, and nature of association of the rock, and then conclude with the very simple theory which I have been tempted to construct from the results afforded me by some experimental researches. The Composition and Constitution of the Rock Dolomite. —In I should say all of the accepted chemical and petrological treatises, even of the most recent date, the statement invariably occurs that the rock dolomite is a double carbonate of calcium (or lime) and magnesium. The seriousness with which this assertion is constantly made, is all the more astonishing when we recollect that the results of all the numerous trustworthy analyses that have been made for the last eighty years are quite antagonistic to it. The well-known dolomite of Faxoe, which was repeatedly analysed by Forchhammer, gave in one sample 97.13 per cent. of carbonate of lime, and 2.87 per cent. of carbonate of magnesia; and in another, 53.38 per cent. of the former, and 41.41 per cent. of the latter salt, and the results of the other analyses were equally divergent. Here, then, a series of very careful analyses by a highly competent man shows how wide a difference exists in quantitive composition between naturally