Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/303

 and exhibits the distinctive characters of the simple mineral, to that in which it is with difficulty perceptible, very little doubt will remain of its existence in the latter.

§ 20. This mineral is not of very common occurrence in its simple state, and is probably less so as a constituent part of a rock; for it is not noticed as such in the Wernerian system, nor am I aware of its being mentioned in any mineralogical work, except in a very few instances. Brongniart, in treating of epidote says, “ This mineral seems to belong exclusively to primitive countries, but it does not usually enter into the structure of rocks. It is found crystallized in the fissures of these rocks, or in the cavities of veins; and even penetrates the substances composing the veins in all directions; it is thus that it traverses carbonate of lime, quartz, &c.” He does not however name any place where it is found to enter into the structure of a rock. Saussure met with it not far distant from Mont Blanc: “ On the road,” says he, “ from Modane to Villa. rodin, in descending the hill above this village, I found in the high road and in the walls of the houses, stones of a very beautiful green, sometimes mixed with white. The green parts, some of which are yellowish-green, having a sparkling lustre, granular and. hard, are of the same nature as the green schorl of Dauphiny. This schorl I name Delphinite, to distinguish it from some other green schorls of a very different nature. These yellowish parts are therefore granular delphinite. The parts of a leek-green, which are inclined in this stone, and which have a schistose or lamellar structure, are hornblende. The white parts are crystalline and granular