4: NEW YORK STATE MUSEUM 



tion embodied in the text. Acknowledgment is also tendered to 

 the gentlemen whose names appear in the list of authorities for 

 local information. 



RELATIONS OF MINEBAJL DEPOSITS TO ROCKS 



By far the greater part of the crystallized minerals of New 

 York State occur in igneous and metamorphic rocks, or grouping 

 these two divisions in a rather broader term, in crystalline rocks. 

 The areas covered by these embrace two important sections of 

 the State; the northern section including the Adirondack region 

 and extending over St Lawrence, Jefferson and Lewis counties on 

 the west and the southeastern section including New York, West- 

 chester, Putnam and portions of Orange, Rockland, Richmond 

 and Dutchess counties. The area of Silurian limestones, ex- 

 tending from west to east across the State just south of Lake 

 Ontario and trending to the south along the west shore of the 

 Hudson, affords many localites for secondary minerals notably 

 calcite, dolomite, celestite, barite, quartz etc. 



Igneous rocks 

 Granites and pegmatites. The component and accessory min- 

 erals of granite are commonly found in independent well formed 

 individuals in cavities or vugs where the open space admits of 

 free development of crystals formed by the separation of the min- 

 eral constituents from the fused rock magma in the process of its 

 solidification. Pegmatite occurring in dikes and veins is char- 

 acterized by the same genetic series of minerals found in granite 

 but commonly in rather larger individuals corresponding to the 

 coarser structure of the rock. 



COMMON MINERALS FORMING AND OCCURRING IN GRANITE AND 



PEGMATITE 



pyrite 



microcline 



epidote 



marcasite 



oligoclase 



allanite 



quartz 



spodumene 



tourmalin 



corundum 



amphibole 



muscovite 



chrysoberyl 



beryl 



biotite 



rutile 



garnet 



titanite 



orthoclase 



zircon 



xenolinie 



albite 



topaz 



apaiilo 



