8 NEW YORK STATE MUSEUM 



minerals found in veins has, however, led the author to consider 

 them under a separate head. The large and important group of 

 vein minerals includes most of the ores of commercial importance, 

 particularly the metallic sulfids and sulfosalts. 



VEIN MINERALS OF COMMON OCCURRENCE IN NEW YORK STATE 



galena fluorite dolomite 



sphalerite quartz siderite 



millerite cuprite strontianite 



pyrrhotite hematite orthoclase 



chalcopyrite magnetite prochlorite 



pyrite rutile barite 



marcasite brucite celestite 



arsenopyrite calcite gypsum 



Minerals produced through pseudomorphism and paramorphism. 

 Minerals included in this group are alteration products of pri- 

 mary minerals. These, while retaining the external form of the 

 primary minerals, from which they were derived, differ essentially 

 from them in composition. 



Drift boulders 



Transported masses of rock are found in all parts of New York 

 State, frequently in boulders of considerable size. These are frag- 

 ments of rock which, through action of glacial or fluvial erosion 

 and transportation have been torn from their parent outcrops and 

 have been carried, generally to the south and east of their ori- 

 ginal sources. The distance which the drift boulder may have 

 been carried by the ice sheet in the glacial period varies widely 

 so that no accurate estimate can be made of the distance be- 

 tween any glacial fragment and its parent mass. 



SOURCES AVAILABLE FOR COLLECTING MINERAL SPECIMENS 



The sources available for the collection of mineral specimens 



may be classified as follows: 



{surface outcrops 

 drift boulders 

 caves 

 mines and quarries 



ITS 



artificial 



excavations for construction : 

 foundations of buildings, 

 sewers, subways 



prospects 



