THIRD REPORT OF THE DIRECTOR I906 27 



in Lewis county. The quarry is on the eastern slope of a ridge of 

 dolomitic Hme§tone extending northeast and southwest, the exposed 

 face rising to a hight of about 35 feet. At a hight of approximately 

 20 feet from the base of this exposed face, the limestone has been 

 hollowed out to form an irregular cavern, the wall, roof and floor 

 of which were covered with calcite crystals, some of enormous size. 

 At the time of the visit a portion of the walls of this cave had been 

 removed in the operation of quarrying the limestone. Access to the 

 cave was gained through an opening about 4 feet in diameter. 

 Inside this opening the cavity expands to a cross-section of about 

 10 feet in width by 5 feet in hight, running back for a distance 

 of some 20 feet when it suddenly contracts to a small passage about 

 4 feet in cross-section, rather winding, but extending downward in 

 a general direction for a distance of about 20 feet, gradually nar- 

 rowing to a size which rendered it impossible of access. 



Many of the largest crystals were found in the outer portion of 

 the cave, the roofs and walls of which were thickly covered with 

 calcite crystals of all sizes. Fewer and smaller crystals were en- 

 countered in the inner cave where they were found mostly attached 

 to the roof and sides. 



The crystals are of unusual size, the largest taken out measures 

 3' 7" by 3' i>^" by i' 6" and weighs approximately 1000 pounds.^ 

 A number of smaller crystals ranging in weight from 100 to 500 

 pounds were obtained, besides several large slabs covered with 

 smaller crystals and a vast amount of small specimens representing 

 single crystals and groups. In all about 12 tons of material of 

 exceptional beauty and interest were taken from this locality. 



In habit the calcite crystals resemble those from Rossie, St 

 Lawrence co. They show a strong tendency toward the fonna- 

 tion of penetration twins parallel to a composition face OP which 

 is present as a well developed plane. This twinning habit finds 

 expression in deep reentrant angles or ''channels," well shown in 

 the adjoining plate and produced by corresponding planes of R 

 (loii) in twinned position. 



On a number of crystals repeated twinning according to this 

 law was noted ; in one instance as many as four repetitions of the 

 twinning habit being observed. The abnormal development of the 

 basal plane produces a tabular aspect quite characteristic of the occur- 

 rence. The lateral edges of the primitive rhombohedron are modi- 



^The largest calcite crystal of which a recordi is accessible is one from 

 Eskifjordhr, Iceland, at present in the British Museum. It measures 

 2' 6" by t' 6". 



