Metastatic crystallized Carbonate of Lime

The present curious production is one of those things that few can expect to possess; therefore it is, like many others in this work, a pleasant proof of the utility of figures, which is certainly next to the possession of the object, as to the instructive information it gives, and the making public those beauties of Nature that must otherwise be ever lost to the scientific world.

I do not know that this formed Crystal has yet been spoken of: Romé De Lisle and Haüy do not mention it. It is in the shelly Limestone which forms one of the upper strata of Derbyshire that this has been formed, hid from mortal ken, within one of the most remarkable species of shells I ever knew, Conchyliolythus productus of Mr. Martyn’s most ingenious work, plate 22. f. 1, 2, 3.

The reason why the primitive molecules should so form, remains a desideratum. We have but just got a notion of the subject, but diligence in this discovering age may yet learn more of Nature’s ways, and even this may be the leading cause: the equally contrariwise attraction of the particles may be governed by the equal evaporation of the fluid in contrary directions, and the gravitation of the solvent medium may poise them to that angle which so nicely replaces them.

One great curiosity of this Mackle is, that the lateral notch at the junction of the two halves at the upper end of the column is very deceiving, being formed from somewhat rounding facets, often scarcely discernible, but by these means become more conspicuous—see the last description.

This specimen was lent me by my friend Mr. Lowry, who met with it last summer, and first discovered this remarkable Mackle.

It is prettily placed in the hollow of the shell among the Limestone, which has on the left hand somewhat enveloped the mineral pitch, and crystallized about the bubbles.