62 JOURNAL OF THE 



ANALYSIS OF CRYSTALS OF DOG-TOOTH SPAR, 

 FROM GANDER HALL, NEW HANOVER 

 COUNTY, N. C, E. SIDE CAPE FEAR RIV- 

 ER, 15 MILES BELOW WILMINGTON. 



W. B. PHILLIPS, PH. D. 



These crystals were found lining the interior of shells, and were 

 first brought to my attention by Mr. Donald McRae, of Wilmington. 

 They presented the usual characteristics of the Dog-tooth Spar, and 

 mention is here made of them on account of their almost perfect 

 purity. Thus for instance, 



weight of crystals taken = .2224 grm's. 



CaCOg found = .22230 



CaO " - =.12448 



CO2 " - = .09782 



yielding CaCOg 99.95 per cent. 



The locality is an interesting one. It is about 1200 metres back 

 from the river, where there occurs a notable deposit of a very 

 coarse-grained coquina. much used by the U. S. government for the 

 break-waters at the mouth of the river. This coquina is obtained 

 from openings in the face of a blufi some four or five metres in height, 

 and the general course of it is parallel with the river. It is of two 

 kinds, fine and coarse, with much intei mixed quartz sand, and con- 

 tains many complete shells of various sizes, besides of course innu- 

 merable small fragments of shells, which constitute the main por- 

 tion of it. The rock is of various degrees of hardness, some of it 

 crumbling under pressure of the hand, and then again requiring a 

 smart blow of a hammer. Exposed to the action of sea water it 

 hardens, and resists the beating of the waves as well or even better 

 than many denser rocks. 



The crystals are found within the larger shells, some of which are 

 7 decimetres long by 4 decimetres wide. Occasionally the coquina 

 completely covers these shells, and on breaking it off the interior of 

 the shell is most beautifully lined with the carbonate, presenting 

 an exquisite appearance, as the pellucid crystals are suddenly 

 uncovered. A most remarkable geological phenomenon is to be 

 seen at this locality, viz : the existence of large pot-holes in the 



