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Updated: May 24, 2025
There was Ferdinand Fitz-Fossillus Feltspar. He informed us all about internal fires and tertiary formations; about aeeriforms, fluidiforms, and solidiforms; about quartz and marl; about schist and schorl; about gypsum and trap; about talc and calc; about blende and horn-blende; about mica-slate and pudding-stone; about cyanite and lepidolite; about hematite and tremolite; about antimony and calcedony; about manganese and whatever you please.
In order to see this, we are to consider that both those substances have specific shapes in which they concrete from the third state; the sparry structure of the one is well known; the spherical or mammelated crystallization of the calcedony, is no less conspicuous; this last is, in the present case, spherical figures, which are some of them hemispheres, or even more.
It is nearly pure in the rock crystal, of which there are many specimens in the first case , including those crystals called Bristol and Gibraltar diamonds, cairngorms, the smoky topaz; rock crystals inclosing foreign substances, and in a wrought state: of these Dr. Dee's snow-stone is one. Upon the last southern table are ranged further varieties of calcedony.
I have good reason to believe that water contained within a solid flint will not make its escape, as does that contained in the anhydrites of Mount Berico, which are composed of a porous calcedony. But the siliceous crystallizations within close cavities is a curious subject, which we shall have occasion to examine more particularly in treating of agates.
It is the case of the calcedony agate, containing a body of calcareous spar; here it is to be shown, that, while the calcareous body was altogether inclosed within the calcedony nodular body, these two substances had been perfectly soft, and had mutually affected each others shape, in concreting from a fluid state.
Now the fact is, that the calcareous body is perfectly inclosed within the solid calcedony, and that they are mutually impressed by each others specific figure, the sparry structure of the calcareous body impressing the calcedony with its type of planes and angles, at the same time that, in other parts, the spherical figures of the calcedony enter the solid body of the spar, and thus impress their mammelated figures into that part which is contiguous.
These include the blood stone; the curious Mocha stones; and agates, including the agate nodule from central Asia. Having sufficiently examined these beautiful varieties of calcedony, the visitor should pass at once to the northern range of tables.
Now, upon this principle, that the agate-calcedony had been formed by fusion, a truth which, from the general testimony of minerals, I must presume, it is plain, that those nodules of gypsum had been in the fluid state of fusion among those marly strata, and that the gypseous bodies had been penetrated variously with the siliceous substance of the calcedony.
In this instance our author had convinced himself that the calcedony concretions had not been formed, as he and other mineralists had before supposed, by means of infiltration; he has not, however, substituted any thing more intelligible in its stead. There is, however, a subject in which I can more freely accuse this author of being deceived.
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