MEMOIR ON EMERY. 11 



run into each other, showing that they are one and the same 

 rock. Had the masses of emery been broken from an older 

 rock and imbedded in the marble at its formation,, there is no 

 reason why the contact should not always be direct and imme- 

 diate without this transition from ferro-aluminous limestone to 

 pure marble. What we see is just what should be expected 

 in ferruginous and aluminous minerals forming and separating 

 themselves from a limestone not yet consolidated. 



This kind of separation between the emery and the marble 

 has been highly useful in the facility that it has indirectly 

 afforded for exploring this mineral. It has been stated that 

 at all the localities under consideration, but principally at 

 Gumuch and Naxos, the emery exists in great abundance, de- 

 tached from the rock, in a red earth; now this earth is simply 

 the result of the decomposition of this heterogeneous calcareous 

 envelope, which from its nature is easy of disaggregation by 

 the influence of atmospheric agents. Had the emery been in 

 immediate contact with the marble, we could hardly have ex- 

 pected this spontaneous separation in so great a quantity. I 

 have in some instances seen small nodules of emery in small 

 cavities in the rock, but perfectly detached. 



3. The immense mass alluded to as covering several square 

 yards of surface is another evidence of the emery having been 

 formed in the limestone, for this mass does not consist of a 

 single piece, but of a number of different sizes, not lying to- 

 gether irregularly, but with their contiguous surfaces more 

 or less parallel, although removed a little distance from each 

 other; in fact, it is just what we would expect in a large 

 mass that for some cause or other had been fissured in various 

 directions. 



4. Yet another circumstance to be remarked in connection 

 with this part of the subject is that in the examination of the 

 surface of contact between the emery and the rock we do not 

 always see it marked by a distinct outline; but the minerals 

 constituting the emery, as well as those associated with it, are 

 more or less disseminated in the limestone at the point of 

 contact. The value of this argument is better understood on 

 examining the specimens in my possession. 



Enough having been said to prove that the emery under 

 consideration was formed within the limestone in which it is 



