MINERALS FROM LYON MOUNTAIN, CLINTON COUNTY 63 



combinations of type V which includes ii of the 19 forms ob- 

 served for the locahty. Assuming the principle announced by 

 €esaro^ "that when a crystal of calcite is formed around a preexist- 

 ing crystal, in general the edges of the first crystal tend to be 

 replaced by faces which are parallel to them; i. e. a face of the new 

 ■crystal is in zone with two faces of the original one." The super- 

 posed groups of type IV present a striking instance of harmony in 

 zonal relations, and indeed the gradual increase in the numbers 

 ■of forms from type I through types III, IV and V shows a close 

 coincidence with Cesaro's principle. 



GENETIC RELATIONS 



In a former paper^ the writer has referred to the pyramidal habit 

 of the calcite crystals of Union Springs and has attempted to con- 

 nect the pyramidal habit with a crystallizing solution heavily 

 charged with dissolved silica. The conclusions drawn from the 

 Union Springs occurrence, where a single pyramid y (8.8.16.3) 

 was used as a basis of comparison between the Union Springs calcite 

 and that from Rhisnes and Andreasberg, gain added force in the 

 case of Lyon Mountain, where a series of four pyramids occur in the 

 various types, all four of which pyra,mids are found on the Rhisnes 

 calcites and three of which also occur on the Andreasberg crystals. 

 The dominant form of a combination illustrated by Luedecke^ 

 under type VIII from Jacobsgltick vein, Andreasberg, /-i (5491), 

 is identical with the dominant form of type I from Lyon Mountain, 

 He notes this type as occurring sparingly with quartz which latter 

 mineral has a "hacked, corroded appearance.'' The mine waters 

 irom this immediate locality carry considerable gypsum, epsomite, 

 limonite and hematite in solution and give evidence of having been 

 strongly corrosive. These facts are in perfect accord with the con- 

 ditions noted in connection with type I from Lyon Mountain 

 [p. 59], and it seems highly probable that in the case of the 

 Jacobsgltick vein, Andreasberg and the Lyon Mountain localities, 

 the first stage of calcite deposition took place from a highly corro- 

 sive solution which was taking up silica while depositing crystals 

 of the steep scalenohedral habit of calcite. The absence of all 

 secondary quartz in connection with this habit in both localities, 

 points to the fact that the primary quartz in both cases was still 



iQ. Cesaro. Les formes crystalline de la Calcite de Rhisnes. Ann. de la Soc. Gaol, de Belgique. 

 1889. 16:167. 



2Whitlock, H. P. Calcite from Union Springs, Cayuga county. N. Y. State Mus. Bui. gS, 

 p. 15-16. 



SLuedecke, Otto. Die Minerale des Harzes, Berlin i8g6, pi. XX, fig. i. 



