NEW YORK MINERAL LOCALITIES 9 



Surface outcrops. The surface outcrops of rocks of all forma- 

 tions but particularly unstratified rocks may be studied with 

 considerable profit by the mineral collector in search of speci- 

 mens. A judicious use of the hammer and cold chisel will often 

 expose, under an unpromising cluster of weathered and decom- 

 posed crystals, fresh material well worth the labor expended 

 on its development. The precipitous faces of cliffs and escarp- 

 ments, furnish in some cases profitable sources for the collection 

 of specimens. 



Drift boulders and fragments. While in some instances drift 

 boulders, notably those composed of crystalline rock, are valuable 

 sources of mineral specimens the uncertainty regarding the origi- 

 nal locality from which they were derived tends to render ques- 

 tionable the value of such specimens. A source of mineral ma- 

 terial which may be classed under this head and which is often 

 of more value than drift fragments embedded in the soil is the 

 fragmental rock material used in the construction of stone walls. 

 The accessibility of these to the roads and the comparative ease 

 with which their component fragments may be identified with 

 the country rock should not be overlooked by the collector par- 

 ticularly in a region of crystalline schists. 



Natural caves. Subterranean tunnels and caverns, formed 

 principally in limestones by the mechanical and chemical erosion 

 of underground waters, frequently become repositories for secon- 

 dary minerals deposited on the sides and roof as a result of the 

 leaching action of percolating surface water. The exploration 

 of these natural caves often results in the discovery of beautiful 

 crystallizations which from the nature of their deposition are 

 readily detachable. 



Mines and quarries. Probably nowhere is the mineral collector 

 better repaid for his trouble than in exploring the dump heap 

 of a mine. The waste material representing, as most of it does, 

 the contents of the contact zone between the vein or ore body and 

 the country rock is usually rich in ore minerals as well as in 

 crystallizations of accessory minerals from the country rock. 

 Similarly but to a somewhat less extent the rejected material 

 from a granite or limestone quarry is a profitable collecting 

 source. 



