THE PHOSPHORITE DEPOSITS OF NORTH WALES. 35' 



23. The Phosphorite Deposits of North Wales. By D. C. Davies, 

 Esq., F.G.S. (Read February 10, 1875.) 



In the year 1863 a working miner picked up a piece of black- 

 looking stuff in a small ravine above Cwmgwynen farm-house, five 

 miles west of the town of Llanfyllin, in North Wales. His dis- 

 covery excited his curiosity, and led him to make some trial-holes 

 in the ravine, in the hope that he might find the substance in bulk. 

 He was successful in this ; but the newly found substance perplexed 

 both himself and his mining friends. It was strange to them all, 

 except that some of them pronounced it manganese, and others 

 rotten sulphur. At last, through the late Mr. Hope Jones, of 

 Hooton, Cheshire, the mineral found its way into the hands of Dr. 

 Voelcker, for analysis. Dr. Yoelcker found that the best samples 

 submitted to him yielded over 60 per cent, of phosphate of lime, 

 and the most impure over 40 per cent. 



At the meeting of the .British Association, in Birmingham, in 

 1864, Dr. Yoelcker called attention to the discovery, and rightly 

 estimated the quantity of phosphate, in the property to which his 

 attention had been directed, at over two million tons. Meanwhile 

 preparations were being made for mining the newly discovered sub- 

 stance, and bringing it into the market. Searches, too, were made 

 for the mineral on adjoining properties, which resulted in its disco- 

 very at Penygarnedd, to the N.E., and Pwllywrach, to the S.W. of 

 Cwmgwynen, under similar conditions. The district was one well 

 known to me previously ; and I had occasion to visit the new work- 

 ings repeatedly. In June 1867 I published in the ' Geological 

 Magazine ' a short account of the deposit, in which I gave illustra- 

 tions of the manner in which it occurred, together with its relation 

 to the surrounding strata. Early in the year 1872 I was asked to 

 examine a similar deposit, which had just been discovered in a like 

 manner at Craig Ehiwarth, in the Berwyn Mountains, between 

 Llangynog and Bala, some six or seven miles to the west of Cwm- 

 gwynen. I at once, as I had anticipated, recognized in the new 

 discovery the old bed, which, though now widely separated from the 

 one first discovered, had evidently once been continuous with it. 



Since then it has fallen to my lot to open up "a mine" at the 

 latter place ; and, partly as a consequence of my connexion with this 

 mine, I have had occasion to visit several other places in North 

 Wales where the deposit has been found. These are as far apart 

 as the vicinity of the town of Llanfyllin, and the hills ranging west 

 and north of Dinas Mowddwy. 



I propose, in this communication, to combine with the remarks 

 made in my paper of 1867 the result of the observations made by 

 me during my closer acquaintance with the deposit during the last 

 few years. 



The deposit occurs in a bed whose geological position is at the top 

 of the Bala Limestone and immediately under the shale by which 



