Handbuch der Mineralchemie

Abstract

No fewer than fifty-five years have passed since the author issued his “Dictionary of the Chemical Part of Mineralogy,” and yet his energy is unabated. The present work is the second supplement to the second edition (1875) of his well-known “Handbuch der Mineralchemie,” a treasury of condensed information relative to the results of the chemical analysis of minerals, and the supplement is a concise record of chemical work on minerals published during the last decade. As in the original treatise, the author restricts himself to the expression and criticism of observed facts, and avoids as far as is possible the discussion or even mention of constitutional formulæ. And for the purposes of the student it is doubtless convenient to have collected for him into a single treatise the observed solid facts upon which all speculation relative to the chemistry of minerals is to be based. Once more the mineralogical chemist is reminded how rarely the analysed material is truly pure, and how necessary it is to record its morphological and physical characters, the mode of its occurrence, and the nature of the accompanying minerals: it is only by regard to such records that the true composition of a mineral can in many cases be deduced. And the author points out how imperfect is our knowledge of the chemical composition of many of the commonest minerals notwithstanding the number of analyses which have been recorded. In the case of the plagioclastic felspars, for example, though the results of many analyses are in close agreement with the hypothesis of the admixture of molecules of albite and anorthite, there are others which deviate considerably therefrom, and are as yet unexplained. The caution of our chemical Nestor is perhaps carried to an extreme. He declines, for instance, to recognise the interchangeability of F and HO, notwithstanding the results independently obtained of each other by Penfield and Sjögren in the case of the Humite group, and by the former in the case of Topaz, and attributes the variations of composition to alteration—to loss of fluorine and gain of water. But in the case of Topaz the angle of the optic axes has been shown to be related to the percentage of the fluorine, and it is difficult to regard the variation of chemical and optica characters to be a result of mere hydration. Every one will hope that the Berlin professor will be spared to issue a third supplement of this standard work of reference.

Handbuch der Mineralchemie.

Von C. F. Rammelsberg, Zweites Ergänzungsheft zur Zweiten Auflage. Pp. 475. (Leipzig: Engelman, 1895.)