Cubical Analcime

Although the Cubic Analcime of Haüy, or what is still by some called Cubic Zeolite, is not rare in some parts of Ireland, especially among basaltic rocks, yet we have had very little account of it. The present specimens were sent me by favour of my friend Mr. Templeton, F. L. S., of Belfast, and were gathered at Cave Hill, near that place. Haüy distinguishes this fossil as having fractures on the six faces^*, or in three directions only; but these specimens are not always easily procured. It is, however, sufficiently distinct from Fluor by its superior hardness, easy fusion into a transparent white glass without ebullition, and want of phosphorescence; having indeed all the characters of tab. 59, except as to form. I have met with impressions of this with other Analcime, as well as small crystals imbedded in the radiated Analcime, or what is by some called radiated Zeolite, in the holes of Basaltic Trap, if I may so call it, for it certainly is not Lava, with which this sort of Trap has been confounded. I hope soon to find an opportunity of explaining the nature of Basalt and Volcanic Trap, which has caused so much argument amongst men of science as to its nature and origin.

The upper specimen shows an almost independent largish crystal.

The lower specimen is a considerable group of small crystals, with sometimes curved or concave faces, marked with diagonal striæ:—see the lateral magnified figure.

This substance in these shapes occurs in many parts abroad, as well as in Scotland; but I do not know that it has been mentioned as found in Ireland till now.