THE CHESTER EMERY BED. 131 



11. Washingtonitk (Ilmenite). 



This species is rarely met with in black foliated, much-curved laminaj betwixt 

 the double seams of margarite. Ou the whole, however, its occurrence is very limited 

 compared with that iu the adjoining mica-slate, to which reference has already been 

 made. 



12. BUOOKITE. 



Only a few crystals of this rare titanic acid have thus far been noticed, and 

 these were found in close connectiou with diaspora. 



13. CiiAXCoPYRiTE (Yellow Copper Ore). 



But few grains of this ore have been seen. It was found, like the washingtonite, 

 in margarite, and also upon the joints of the gneiss near the emery vein — in the 

 latter case attended sometimes by stains of malachite. 



The foregoing are all the species thus far found as proper to the vein, with the 

 exception of two apparently rare instances — one in small brown and copi)er-colored 

 prisms somewhat resembling tyrite, the other in orange colored specks (slightly 

 decomposed) upon the joints of the emery, and sometimes disseminated through the 

 chlorital gangue, both of which await examination. 



Outside of the vein with the talcose slate, besides the sparsely diffused grains 

 of emery and magnetite, a greeuish-white laminar talc in thin seams occurs sometimes, 

 penetrated by a greenish yellow actinolite. But the most important mineral economic- 

 ally is that modification of the talcose slate recognized under considerable variations 

 of character as soapstone. It is here found in immense quantity at several points ou 

 the course of the vein, but nowhere, perhaps, in a more promising condition for being 

 wrought than near the works upon the South Mountain. It here quarries with much 

 facility in virtue of the natural joints by which it comes out in blocks of from 4 to 6 

 feet superficially, with a thickness of at least 1 foot, often 2 or more feet. It has the 

 further recommendation of being free from those foreign minerals so frequently 

 interfering with its easy division into slabs in the process of sawing. 



It is a point of some importance to notice the correspondence between the 

 minerals enumerated in this paper and those described by Prof. J. Lawrence Smith iu 

 his report ^ as occurring at the Turkish and Grecian localities of emery. He concludes 

 his account of these with the following observations : " 1 do not risk much in saying 

 that the hydrate of alumina (diaspore), as well as the silicates emerylite (margarite), 

 chloritoid, and tourmaline, and the ores of iron (magnetite) and titaniferous iron 

 (ilmenite), wiU be found almost everywhere with the emery and corundum." 



It will also occur to the chemical geologist and mineralogist that we are now 

 furnished with an explanation of the uufrequency of the corundum and spinel families 

 of minerals, since their formation presupposes the existence of alumina, not only in 

 excess, but attended by the absence of silica; while for the formation of emery there 



' See Am. Jour. Sci., 2d series, Vol. XI, January, 1851. 



