18 Bulletin of the New York State Museum. 



the " allotriomorphic " and " riliomorphic," designated by the same 

 .author, could be explained by means of the well founded assumption 

 of more rapid crystallization of some minerals than others. 



From the well known homogeneity of granites and gneisses this 

 inference can be legitimately drawn. At the same time, it is easy to 

 imagine exceptions to these circumstances which would allow a 

 mineral to assume its own form with greater or less perfection, and 

 such exceptions are actually found. Let a cavity, however small, be 

 formed in a rock undergoing metamorphism and it will bristle with 

 crystals either of quartz, feldspar or mica or all together. It will also be 

 readily called to mind that in coarsely crystalline rocks that the 

 quartz is usually the gaugue in which perfection of form most readily 

 occurs. Minerals, such as spodumene, feldspar, beryl, triphyllite, 

 tourmaline, etc., which are found at the spodumene locality at Hun- 

 tington, Mass., have great perfection of form, irrespective of size, so 

 long as they are developed in quartz, but at once lose their individ- 

 uality when masses of feldspar and mica occur. It is quite rare to 

 find these minerals in the feldspar and mica, but when they do thus 

 occur they are invariably misshapen. To those who are familiar 

 with the occurrence of zinciferous minerals in the calcite gansrue of 

 the Franklin Furnace and Ogdensburg zinc mines in New Jersey, 

 additional facts will readily offer themselves. It is comparatively rare 

 in these localities to find minerals in the gangue with sharp augles 

 and perfected forms. 



Among miners the term " shot ore " is employed to designate a 

 mass of ore perfectly crystalline and well individualized save external 

 form. This external form is produced by the great amount of mineral 

 matter attempting to crystallize in a limited space. The phenomenon 

 is noticed more frequently in iron and zinc ores, but it is by no means 

 confined to them. In the garnet beds or pockets so abundant in 

 Warren and Essex counties, N. Y., by far the greater number of 

 these deposits break up in a manner exactly similar to the " shot 

 ores" of the miners. In one place in Thurman, N. Y., a bed or 

 pocket of hornblende is similarly formed. 



Again the deformation and distortion of nearly every species of 

 minerals, deposited from solution, in space, limited either by size of 

 cavity or by interference with each other, are ample evidence that such 

 distortion may occur from crowding. Evidence might be also adduced 

 from the class of pseudomorphism where one mineral fills a cavity 

 formed by another, which has been removed by solution. The same 



