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pentine scattered more or less evenly through its mass. Its orna- 

 mental quality lies in the speckled or mottled pattern and the sharp 

 contrast between the clear white mass and the greenish serpentine 

 inclusions. 



Marbles belonging to those various types find representation in 

 the geologic formations of the State and are quarried on a commer- 

 cial scale or have been so quarried in the past. 



The true or crystalline varieties are limited in occurrence to the 

 metamorphic areas of the Adirondacks and southeastern New York. 

 They are of early geologic age, antedating the period of crustal dis- 

 turbance and metamorphism which in the Adirondacks was brought 

 to a close practically before Cambric time and which in southeastern 

 New York was completed in the Paleozoic. This thoroughly crys- 

 talline character is in fact a development of the strong compression 

 accompanied by heat to which they have been subjected ; having been 

 originally, no doubt, ordinary granular or fossiliferous limestones 

 similar to those so plentifully represented in the undisturbed forma- 

 tions outside the regions. 



The crystalline limestones of the Adirondacks are most abundant 

 on the western border in Jefferson, Lewis and St Lawrence coun- 

 ties where they occur in belts up to 4 or 5 miles wide and several 

 times as long, interfoldedand more or less intermixed with sedimen- 

 tary gneisses, schists and quartzites. They are found in smaller and 

 more irregularly banded areas in Warren and Essex counties on the 

 eastern side, but have little importance elsewhere. The ophitic lime- 

 stones that have been quarried at different times belong to the same 

 series. The marbles of the Adirondacks comprise both the calcite 

 class with very little magnesia and the dolomite class containing high 

 percentages of magnesia. No definite relation is apparent in regard 

 to the occurrence of the two and both may be found in the same area 

 and in close association. 



The southeastern New York marbles occur in belts which follow 

 the north-south valleys, east of the Hudson, from Manhattan island 

 into Westchester, Dutchess and Columbia counties. They range 

 from very coarsely crystalline to finely crystalline rocks, are prevail- 

 ingly white in color and belong to the dolomite class. They are 

 interfolded with schists and quartzites, the whole series having steep 

 dips like those of strongly compressed strata. The geologic age of 

 the southern belts is probably Precambric, but on the north and east 

 within range of the Taconic disturbance, they may belong to the early 

 Paleozoic. 



