628 CLEMENT LE NEVE FOSTEE's NOTES ON HAYTOE IEON-MINE. 



46. Notes on Hattoe Ieon-mine. By Clement Le Neve Postee, 

 B.A., D.Sc, F.G.S. (Read June 23, 1875.) 



It is nearly fifty years since this mine first attracted the attention 

 of mineralogists by the occurrence of haytorite ( chalcedony, pseudo- 

 morphous after datholite). Several papers on the mineral were 

 contributed to the Philosophical Magazine * ; and an account of the 

 mine was given by Mr. J. T. Kingston f. His description deals 

 with the beds seen in an open work, and is so full and clear that 

 there would be little left to add were it not for the fact that a new 

 adit-level has intersected the beds and exposed a new section. There 

 are certain points in this section which I think are worthy of being 

 recorded ; besides which it is well to call attention to the fact that 

 there is now a good opportunity of studying the mode of occurrence 

 of a fine deposit of magnetite without the necessity of making a 

 journey to Norway or Sweden. 



Haytor Mine is situated on the eastern borders of Dartmoor, 

 about three quarters of a mile from the pile of granite rocks from 

 which it derives its name. The iron- ore occurs in the form of 

 thick beds of magnetite inter stratified with altered shales and sand- 

 stones of Carboniferous age. Near the iron-ore the rock becomes 

 highly charged with hornblende, and is sometimes apparently entirely 

 made up of actinolite. Garnets, too, occur in great abundance in 

 some places ; and I also found a thin layer containing iron pyrites 

 and what appears to be axinite. 



The section seen near the end of the adit-level is shown in fig. 1. 



Fig. 1. — Section in the Adit-level in Hay tor Mine. 



Scale 



a [ | Siliceous slate and Actinolite rock. 

 & K-vy:'-1 Magnetic Iron-ore. 

 Granite vein. 



The exact thicknesses of the various beds were not measured by me, 

 but were taken by the agent of the mine, Captain William Grose. 



* The Philosophical Magazine, vol. i. 1827, pp. 38, 40, 43 ; vol. x. 1831, 

 p. 111. The Edinburgh Journal of Science, vol. vi. pp. 297 & 301. 

 t The Philosophical Magazine, vol. iii. 1828, p. 359. 



