o5 [Jackson. 



scratch quartz crystals. In a few weeks he sent me some pieces of a 

 mineral which the -workmen said "wore out forty drills in boring a 

 single hole for blasting." and on phvsical, chemical and microscopical 

 examination, it proved to be identical with the emery of Xaxos. with 

 which it was compared. It was found to scratch quartz and topaz 

 readily, and I cut a face on a crystal of quartz with its powder spread 

 with water on a plate of iron. Chemical analysis showed it to consist 

 essentially of Alumina cind Protoxide of iron, and it5 specific gravity 

 was near that of the Xaxos emery. 



On the 11th of October last, in company with Mr. Taffc and several 

 of his associates. I re-visited Chester with a view to a ftill examination 

 of the localities for emery, and was surprised to find that one of the 

 beds we had aU supposed to be magnetic iron ore. and trom which hun- 

 dreds of tons had been taken and smelted with the ores of iron in 

 Berkshire county, was really composed chiefly of pure emery, only a 

 part of the bed being properly an iron ore. Had not the occurrence 

 of Margarite and Chlorotoid called my attention to the probable 

 existence of emery at this locality, it would have been overlooked to 

 this day. and no one knows for how long. 



I mention this, as an example of the real uses of supposed useless 

 minerals. They are. to an experienced mineralogist, the guides which 

 point to other and often valuable discoveries. There are many 

 instances in which, by following such indications, valuable ores, be- 

 fore unknown in a district, have been discovered, and they have also 

 been the means of discovering other minerals interesting to science. 

 I would here express my obligations to J. L. Smith of LouisviUe. Ky., 

 for his valuable contributions to our knowledge of the associated 

 emery minerals of the Grecian Archipelago and Asia Minor, published 

 in the tenth and eleventh volumes of the American Journal of Science, 

 in 1850 and 1851, and for a series of those minerals which he sent me, 

 at that time ; since that information aided in the prediction which I 

 made respecting the occurrence of emerj- in Chester. 



The principal bed of emery, in the South Mountain in Chester, is 

 fi^m four to ten feet in width, and is now quarried at the base of the 

 hill. Its course is nearly N. 20- E.. S. 20^ TV., and its angle of 

 dip is 70° eastward. The bed widens rapidly as it rises in the 

 mountain, and is in one place, where it is associated with a bed of iron 

 ore, seventeen feet wide, the emery itself being not less than ten feet 

 in the clear. The highest point where it outcrops is seven hundred 

 and fifty feet above the immediate base of the mountain ; the bed 

 cuts through both the South and the North Mountains, and has been 

 traced, in length, four miles. The depth to which it penetrates below 

 the lowest point seen must be very great, so that we may say without 

 exaggeration that it b inexhaustible. I noticed some very curious 



