Organic Acids in the Examination of Minerals. 



Since the hardness, coherence, and solubility of minerals 

 vary greatly in different specimens of a single species, the 

 behavior of minerals with acids, whether inorganic or organic, 

 depends in large measure upon the condition of the particular 

 sample under examination. An absolutely thorough investi- 

 gation, therefore, would embrace the reactions of several 

 specimens of each mineral ; as desirable as this would seem to 

 be, it was found that on the whole so laborious an undertaking 

 was superfluous, and for two reasons ; first, the decomposing 

 action of the acids on different samples of the same species 

 differs in degree and not in kind; and, secondly, the behavior 

 of different species nearly related is so similar that the obser- 

 vations made on each serve to mutually control. 



2. The following list contains the names of the minerals 

 which were submitted to the action of organic acids, their 

 formulae as given by Prof. Dana, the condition of the speci- 

 mens, and the locality of each so far as could be ascertained. 

 Where two or more specimens of a single species are named, 

 they are numbered, for convenience of reference in subsequent 

 pages. 



Within the groups I, Carbonates ; II, Sulphides ; III, Ox- 

 ides ; IV, Sundries ; V, Silicates, the minerals are given in 

 the order, and with the formulas, which they have in Dana's 

 System of Mineralogy. 



I. CARBONATES. 



Description. Locality. 



fine-grained marble Italy. 



transparent crystals Bergen, N. J. 



coarse crystalline Westchester Co., N.T. 



( fine granular, with ) Am1tv N Y 

 \ flakes of graphite, f Amlt y. «• * • 



massive, subtransl Montville, N. J. • 



crystalline Nova Scotia. 



massive Westchester, Pa. 



compact Piedmont. 



massive Roxbury, Conn. 



massive Dauphiny, France. 



massive, pure Austin, Nev. 



earthy, massive Sterling, N. <T. 



Mineral. 



Formula. 



Calcite, (1) 



CaC 



" (2) 







Ca C + Mg 



" (2) 







2Ca C + MgC 





CaC+(MgFeMn 



Magnesite, (1) 



MgC 



(2).... 







FeC 



" (2) 





Rhodochrosite . . . 



MnC 





ZnC 



