14. It will be objected[63], that the crystalline form ought not to be made the dominant character in mineralogy, since it rarely occurs perfect. To this it is replied, that even if the application of the principle be difficult, still it has been shown to be the only true principle, and therefore we have no alternative. But further[64], it is not true that amorphous substances are more numerous than crystals. In Leonhard’s Manual of Oryctognosy, there are 377 mineral substances. Of these, 281 have a crystalline structure, and 96 only have not been found in a regular form.
[63] Règne Mineral, p. 79.
[64] Ib. p. 82.
Again, the 281 crystalline forms have each its varieties, some of which are crystalline, and some are not so. Now the crystalline varieties amount to 1453, and the uncrystalline to 186 only. Thus mineralogy, according to the view of it here presented, has a sufficiently wide field[65].
[65] Ib. p. 84.
15. It will be objected[66], that according to this mode of proceeding, we must reject from our system all non-crystalline minerals. But we reply, that if the mass be composed of crystals, the size of the crystals makes no difference. Now lamellar and other compact masses are very generally groups of crystals in various positions. Individuals mutilated and mixed together are not the less individuals; and therefore such masses may be treated as objects of natural history.
[66] Ib. p. 86.
If we cannot refer all rocks to crystalline species, those which elude our method may appear as an appendix, corresponding to those plants which botanists call genera incertæ sedis[67].
[67] Ib. p. 91.
But these genera and species will often be afterwards removed into the crystalline part of the system, by being identified with crystalline species. Thus pyrope, &c., have been referred to garnet, and basalt, [151] wacke, &c., to compound rocks. Thus veins of Dolerite, visibly composed of two or three elements, pass to an apparently simple state by becoming fine-grained[68].