Prof. Vanuxem on the Marmolite of Mr. Niittall. 91 



Bare Hills. Hobokeu. Precious Serpentine. 



Silex .... 42-69 40 V2 



Magnesia ... 40 42 40 



Water . . . 16-11 16-45 14-38 



Deutoxide of iron 1*16 -90 1 



Loss .... -4 -65 2-62 



100 100 100 



By comparing the above analyses with the analyses of the 

 precious and all the hydrous serpentines, no real difference 

 fcan be perceived ; hence we must conclude them all in that 

 respect to be the same. Mr. Nuttall, on the ground of che- 

 mical composition, is of opinion that marmolite might equally 

 *' be referred to talc or steatite." Now all well characterized 

 talc contains much more silex, less magnesia, and less water, 

 in the proportion of about 62-5 silex, 31-5 magnesia, and 6 

 water. As to steatite, 1 can only consider it as a rock of 

 which talc is the basis ; and hence its composition may vary 

 by admixture with other rocks or minerals, as is the case with 

 every great mass of mineral matter. I have no doubt that 

 among the many analyses we have of the substances arranged 

 under steatite the marmolite may be found, and probably 

 even also among the diallage, bronzites, &c., though in an im- 

 pure state. 



To conclude : The marmolite corresponds with serpentine 

 in all its important characters ; to wit, composition, infusibility, 

 hardness, and specific gravity : also in those characters of less 

 importance; as colour, fracture not dependent upon internal 

 arrangement of particles, lustre of the same, &c. ; and differs 

 only as to crystalline structure, and lustre thereon depending ; 

 both of which circumstances belong to every mineral species 

 which present crystallized and compact varieties. 



All mineral substances are identical that agree in composi- 

 tion, hardness, specific gravity, and primitive form or crystal- 

 lization; — but the absence of the latter character, so far from 

 making a specific difference, is merely considered in the light 

 of an accident. Conceiving then the identity of the marmo- 

 lite and serpentine to be fully proved, we shall have three 

 sub-species or varieties of this mineral, according to the idea 

 or importance attached to these sub oi* minor distinctions. 

 1st Sub-species. Marmolite or lamellar 5 rare, forms masses not exceeding 



Serpentine, ( a few inches in diameter. 



2d Do. Precious or compact C more abundant ; but if it forms 



translucent Serpen- < rocks, they are of very limited 



tine ( extent. 



3d Do. Common or Serpen- ( forms rocks of great magnitude, 

 tine rock ( often very impure. 



M 2 XV. An 



