He claims that the minerals and rocks composing the earth's crust are all of organic origin, including even granite.

The thickness of this crust he thinks, in the absence of positive knowledge, to be from three to four leagues, or from nine to twelve miles.
After describing the mode of formation of minerals, including agates, flint, geodes, etc., he discusses the process of fossilization by molecular changes, silicious particles replacing the vegetable or animal matter, as in the case of fossil wood.
While, then, the products of animals such as corals and molluscs are limestones, those of vegetables are humus and clay; and all of these deposits losing their less fixed principles pass into a silicious condition, and end by being reduced to quartz, which is the earthy element in its purest form.

The salts, pyrites, and metals only differ from other minerals by the different circumstances under which they were accumulated, in their different proportions, and in their much greater amount of carbonic or acidific fire.
Regarding granite, which, he says, naturalists very erroneously consider as _primitive_, he begins by observing that it is only by conjecture that we should designate as primitive any matter whatever.

He recognizes the fact that granite forms the highest mountains, which are generally arranged in more or less regular chains.

But he strangely assumes that the constituents of granite, _i.e._, felspar, quartz, and mica, did not exist before vegetables, and that these minerals and their aggregation into granite were the result of slow deposition in the ocean.[80] He goes so far as to assert that the porphyritic rocks were not thus formed in the sea, but that they are the result of deposits carried down by streams, especially torrents flowing down from mountains.