MEMOIR ON EMERY. 



37 



The minerals which are brought under this species are the 

 chloritspath or chloritoid of the Ural, the Sismondine of St. 

 Marcel, and the Masonite of Ehode Island; their analyses and 

 formulas are as follows: 



Silica 



Alumina 



Protoxide of iron 



Magnesia 



Water 



I. 



c 



<<! 

 0Q 

 CD 







II. 



o 



X 



2 

 2 



III. 



o 



'ii 



2 



IV. 



o 



era 

 a 

 a 



V. 



o 



CD 

 3 



VI. 



27.48 



6 



24.40 



24.1 



9 



28.27 



6 



25.18 



5 



23.91 



35.37 



6 



45.17 



3 



44.2 



15 



32.16 



6 



33.61 



6 



39.52 



27.05 \ 

 4.29/ 

 6.95 



3 



30.29 



1 



23.8 



4 



33.72 



3 



35.31 



3 



28.05 



3 







7.6 



5 



5.00 



2 



5.88 



2 



7.08 



I. Chlorite spar or Chloritoid of the Ural by Bonsdorff. (Fe, Mg) 8 Si+ 

 £l 2 Si+3H. 

 II. Chlorite spar of the Ural, Erdmann. Fe 3 3tl+23cl Si. 



III. Sismondine of St. Marcel, Delesse. Fe 4 Si 3 +5*1 H. 



IV. Masonite of Ehode Island, Whitney. Fe 3 gi-f 3fcl a Si+2H. 



V. Chlorite spar according to Rammelsberg requires 3R 3 Si+2^cl 3 Si-f 6H. 

 VI. Chrilotoid of Asia Minor, J. L. Smith. £l 3 Si+Fe 3 Si+3H. 



This mineral is found very abundantly with the emery of 

 G-umuch-dagh; it covers the surface of the blocks, and some- 

 times enters largely into the substance of the emery. It is easy 

 to see from the composition of this mineral that it is formed by 

 elimination from the mass of emery at the time of its consoli- 

 dation, which by this means tends to purify itself. The nodule 

 of which I have already spoken under the head of emery and 

 of emerylite goes to sustain this view of the question. 



On the emery of the other localities I have not found this 

 chloritoid. Its composition is not in perfect accordance with 

 the known varieties of chloritoid. and differs from Sismondine 

 (which it approaches most in composition) by its imperfect 

 solubility in hydrochloric acid. 



BLACK TOURMALINE. 



This mineral is found abundantly with the emery of ISTaxos, 

 and also in small quantities with that of other localities. It 

 appears to have replaced the chloritoid that is found so abun- 

 dantly with the emery of Gumuch-dagh. 



The crystals are found agglomerated on the surface, and also 

 disseminated in the interior of the emery. This mineral, like 



3 



