580 PHILOSOPHICAL TRANSACTIONS. [aNNO 1775. 



irregularly almost, as the prisms in a mass of common crystal. Nor is this 

 variety of position so observable in single columns, as in whole masses or ranges 

 of them, which often present themselves in the same hill, disposed in different 

 strata or stages, as it were, one above the other, many of which affect very dif- 

 ferent, and even opposite directions. The columns of San Giovanni seem 

 bedded in a kind of vulcanic sand, which, in many parts of the hill, entirely 

 covers them ; these however probably rest at bottom on a base of basaltine rock 

 of the same nature. Nothing is more common in the provinces of France just 

 mentioned, than to see isolated basaltine hills almost exclusively composed of 

 different layers of columns, which present themselves in stages, one above the 

 other, often without any other stratum between them, resembling, in some 

 measure, si magna licet componere parvis, a huge pile or stack of eleft wood. 

 Though the columnar crystallization of Monte Rosso is the only one I have yet 

 seen, or heard of, in a mass of granite, yet other groups of columns have 

 occurred to me in other parts, that are equally of a heterogeneous substance or 

 texture, though different from those of Monte Rosso, as well as from the com- 

 mon basaltes. 



These systematic mineralogists, in general, assign the same common origin to 

 most lapideous solids, which they suppose to be generated by deposition from an 

 aqueous fluid. In whatever manner therefore the prismatic bodies in question 

 are classed, on such a principle, no adequate idea can thence be ascertained con- 

 cerning their origin, which seems manifestly different. For surely the structure, 

 and other phenomena of these bodies, sufficiently prove them to be crystalliza- 

 tions or concretions of a particular kind, and generated immediately from an 

 igneous fluid : for they are not only peculiar to vulcanic tracts of country ; but 

 differ, in every respect, from common crystals produced from an aqueous fluid. 

 Every one knows, that the latter are formed stratum super stratum, by a slow 

 and successive deposition and juxta-position of parts, as hath been proved satis- 

 factorily by Cappeler, Linnaeus, and other writers on this subject. The same 

 mode of generation is more particularly explained by Steno, in his excellent trea- 

 tise De Solido intra Solidum Naturaliter Contento. But this mode does not 

 seem at all reconcileable with the basaltine crystallizations in question. For 

 however these bodies may vary in their texture, yet none of them afford the 

 least indication of an origin common to other crystals ; but seem rather the 

 effects of some intrinsic principle of organization, by which they appear to have 

 been produced simultaneously, in a manner, on the consolidation of the whole 

 mass of matter, in which they lie, and with which they constantly bear the 

 greatest analogy, as before observed. It is further remarkable, that common 

 crystals are parasitical bodies ; whereas basaltine crystallizations, notwithstanding 

 the peculiarities of their figures, rather seem to form integral parts of the masses 



