for curiofity, than for ufe. Inftigated by this motive, and at the defire of my friend Mr. Cooper, I have undertaken to lay before the Society an account of the only mine in England* in which, according to the best of my information, any Aerated Barytes has been discovered. At the fame time I fhall fubmit the few obfervations which two fhort vifits have enabled me to make upon the natural history of a foffil, concerning which the curiofity of Mineralogifts has been excited, but never gratified.

The first intimation of the Aerated Barytes exifting naturally, was given by Dr. Withering, who published an excellent analysis of it in the Philofophical Transactions, for the year 1784, wherein he has left us little to defire respecting its chemical properties. However he was mifinformed as to the place from whence his fpecimen came, which he supposed to be Alfton Moor, where I have good authority for advancing, that none has been found. He has fince informed me that he believes it came from the fame mine of Anglezark, which forms the fubject of the present paper.

* In Scotland it has been found in the mines of Strontain and Dunglafs, near Dumbarton, but I have not heard of its being yet difcovered on the Continent. A Foffil fent from Scotland to Dr. Crawford, as the Aerated Barytes, and not very diffimilar in its external appearance, feems from his experiments to contain a perfectly New Earth.

The Mine of Anglezark lies within a district of the fame name, fituated on the property of Sir Frank Standish, Bart. about three miles to the east of Chorley, in this county. The country is hilly and of a stratified or fecondary nature, confifting of alternate ftrata of Sand-ftone and Argil, laceous Shiftus, interlaid here and there with thin beds of Coal. The Valley, which is traverfed by the principal Veins, ruhs in an easterly direction the hills on both fides of it are low, though of fteep afcent. I found the Strata upon the south fide of it, in the Shaft called the New Engine Shaft, to follow one upon another in the following order and thickness.

yard loose Stones and Sand.

7 yards Sand-stone.

yard Argillaceous Shiftus and Coal. 1 yard Argillaceous Shiftus,

I

16 yards Sand-ftone.

16 yards Argillaceous Shiftus.

42 yards whole depth of the Shaft.

In the laft ftratum, in another part of the mine, an Under-ground Shaft has been funk eleven yards deeper, in working which they cut through two or three small beds, about a foot in thickness, of an exceeding hard bluish Sand-stone.

The Sand-ftone which forms the second and fifth ftrata, confifts of small angular particles of Quartz, interfperfed with others of Mica, and agglutinated

by

by an argillaceous cement, fo as to form a very hard aggregate of a reddish grey colour.*

The Argillaceous Shiftus, which is called Shiver by the miners, differs little from that which is in general found incumbent upon Coal. It appeared to contain no marine exuviæ, but abundance of thin laminæ of Martial Pyrites between its plates; at least this was the cafe with those pieces which were found near the vein.

The Strata dip from East to West, with a general declivity of about five inches in two yards. Those on the North fide of the veins, or towards the valley, lie fix yards deeper than the correfponding ones on the South.

* I have no doubt that these Strata of Sand-stone, as well as many others of the fame nature, originate from Granite Mountains, which in some of the great revolutions of the globe, were in part destroyed, or wafted by the violence of the waters, forced along with the irresistible torrents, and by them conveyed to, and depofited in the beds where we now find them, where they afterwards confolidated. I am led to this conjecture, not merely from the general method of accounting for the formation of Stratified or Secondary Mountains, but more especially from having obferved in thefe Sand-ftones all the component parts of Granite, Quarz, Mica and Feltfpar, the last of which in general forms the cement, though diftin&t cryftals of it are alfo interfperfed in the maís.

+ Vide Forster's Introduction to Mineralogy, Shiftus friabilis, p. 14; alfo Berkenhout's Natural Hiftory of Great Britain, part III. p. 14. It is omitted in Kirwan's Mineralogy, as alfo in Magellan's Cronstedt.

The