74 NEW YORK STATE MUSEUM 



GENERAL CONCLUSIONS 



The occiirrence at Lyon Mountain of two distinct phases of a 

 mineral species, as has been noted in the cases of quartz, calcite, 

 the feldspars, amphibole and apatite, points unquestionably to 

 two distinct periods of mineral deposition. Of these, the first may 

 be said to be characterized by the production of large crystalliza- 

 tions from an aqueo-igneous fusion, of which the superheated 

 water acted as a powerful solvent. The marked prevalence of 

 natural etched pits on the surface of the minerals of this phase, as 

 well as their partial resolution bears evidence of the potency of 

 this dissolving action. Considerable mechanical stress accom- 

 panied the formation of the minerals of this period and the evidence 

 is not lacking that the perfectly formed minerals were still in a soft 

 or pasty condition when subjected to external pressure. 



The second stage of mineral production, which is marked by 

 smaller and more perfectly crystallized individuals, was the result 

 of recrystallization of the dissolved materials from the saturated 

 aqueous solution, the dissolving action of which is apparent in the 

 minerals of the first period. In some instances this second period 

 may have been contemporary with the first, as in the case of the 

 calcite of type I. In general, the minerals of secondary derivation 

 are to be found incrusting those of the previous generation indicat- 

 ing a complete change in the mode of production. 



