ELIZABF.THTOWN AND PORT HENRY QUADRANGLES 1 55 



In the pegmatitic aggregates from the Barton Hill mines, apatite 

 appears in green hexagonal prisms, up to half an inch in diameter. 

 It has also been noted as an inclusion in titanite, having preceded 

 this mineral in time of formation. The angles of the crystals are 

 more or less rounded as so often happens with this mineral. , 



Arsenopyrite is of rare occurrence in the coarse pegmatite of 

 the "21" mine. It is associated with quartz, orthoclase, albite 

 and zircon. Although as a rule in thin seams long cracks and 

 cleavage planes, one specimen was found, about ^ inch long, 

 by ys inch broad and thick. It had, however, but one crystal face. 



Biotite occurs in the coarse pegmatitic aggregates of the iron 

 mines, and in the bunches of silicates in the Grenville limestone 

 Ciuarries. It seldom exhibits crystal boundaries. 



Calcite. This mineral is of course present in the GrenviUe 

 limestone quarries aiid is occasional in the mines at Mineville. 

 The most interesting occurrence is one discovered in 1888 by Mr 

 W. H. Benedict, then principal of the Port Henry High School. 

 The crystals were measured and figured by the writer in a brief 

 note in the American Journal of Science for July 1890, page 62, 

 and the figure is reproduced in the 6th edition of Dana's System 

 of Mineralogy. Upon the faces of the unit rhombohedron, with sub- 

 ordinate 4R, are superimposed two scalenohedrons whose combina- 

 tion oscillating with R builds up a low^ four-sided pyramidal form. 

 The two scalenohedrons gave f R f and ti" R f 



At Mineville the calcite appears in crusts consisting of well 

 developed — ^- R. The IMiller pit has furnished the best speci- 

 mens but they are not common. 



Diopside, see under Pyroxene. 



Feldspar. Albite has already been noted above. Oligoclase in 

 great cleavage pieces has been collected from the old Cheever mine 

 dumps and exhibits especially fine striations. Similar cleavage 

 pieces may often be obtained from the pegmatitic masses of the 

 other mines. Labradorite is in endless quantity in the anorthosites. 

 In the mountains along the Schroon valley it can be sometimes 

 obtained in fairly good pieces, but as a rule throughout the area, 

 the anorthosites have been so excessively granulated as to destroy 

 the larger crystals. Orthoclase is common in the pegmatites but is 

 seldom well crystallized. Yet in the area just south in Crown 

 Point huge and well developed orthoclase crystals occur. 



Fluorite of massive character and not displaying other than 

 cleavage faces ccurs in great abundance in the Barton Hill ore 

 bed. The new tunnel which has been recently run from the Arch 



