Note 34 — Chapter II · (continued 4)
Reading edition
Footnote 34:
(return)
The Chevalier Dolomieu makes the following observation. Journal de Physique, Juillet 1791.
"J'ai été étonné de trouver au centre d'un énorme massif de granit, que l'on avoit ouvert avec la poudre pour pratiquer un chemin, des morceaux, gros comme le poing et au dessous, de spath calcaire blanc, très-effervescent, en grandes écailles, ou lames entrecroisées. Il n'occupoit point des cavités particulières, il n'y paroissoit le produit d'une infiltration qui auroit rempli des cavités, mais il étoit incorporé avec les feld-spath, le mica, et le quartz, faissoit masse avec eux, et ne pouvoit se rompre sans les entraîner avec lui."
This great naturalist is convinced that the spar had not been here introduced by infiltration, although that is the very method which he employs to form concretions, not only of spar but of crystal, zeolite, and pyrites, in the closest cavities of the most solid rocks of basaltes. These four substances in this stone were so mixed together that nothing but the fusion of the whole mass could explain the state in which they appeared; but, thinking that such a supposition could not be allowed, this naturalist, like a man of science when his data fail, leaves the matter without any interpretation of his own. This however is what he has not done in the case of basaltes, or that which he mistakes for proper lavas, as I shall have occasion to show.