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 eroup 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: 
f , surface outcrops — 
natural { drift boulders 
| 
| | caves 
Sources ; ; mines and quarries ~ 
excavations for construction : 
artificial J foundations of buildings, 
| sewers, Subways 
[ . | prospects 
‘a 
