JETawkins — Mineral Occurrences at Princeton^ N. J. 449 



bed. There are also in this latter material some crystals, all 

 much flattened on account of their growth in a narrow 

 cavity. An analysis of the massive mineral, by Prof. A. H. 

 Phillips, gave : 



A1 Q 3 23-58 per cent 



Na 2 14-35 " " 



Si0 2 53-79 " " 



HO 835 " " 



Total 100-07 



u a 



This approximates closely to the average composition of typical 

 analcite. 



Barite. — From McCarthy's quarry, Princeton. Crystals of 

 dimensions ranging up to l cm X '5 cm and larger ; translucent ; 

 color a delicate pink. The best crystal (fig. 2) obtained was 

 measured, and was found to yield the following common 

 forms : m(110), c(001), a (100), -w(lOl), <Z(102), o (Oil), s (111), 

 2/(122). 



Chlorite. — Dark green, minutely flaky masses of chlorite, 

 resembling the variety known as delessite. It occurs in iso- 

 lated masses on the analcite, enclosing ilmenite rosettes. 



Pyrite. — Abundant ; some complicated crystals in open cav- 

 ities. One of these latter crystals, less than l mm in diameter, 

 was of octahedral habit and showed the following forms : 

 p (111), a (001), d(l01), n (311), <?(210). 



Calcite. — One small crystal of calcite from Princeton,_ of 

 rhombohedral habit, showed the forms : r (1011), m (1010), 

 c (0001). A crystal from the northernmost quarry on the Penn- 

 sylvania side of the Delaware River, in the vicinity of Scud- 

 ders Falls, was a combination of e (0112) and m (1010). 



Quartz. — The Delaware River quarry (described under Cal- 

 cite) afforded some well crystallized quartz. A crystal -5 cm 

 long and '2 cm in diameter, transparent and d_oubly terminated, 

 showed the following forms : ^(1011), s(Olll), * (1121). 



Par agenesis of the Minerals. — The brookites and the ilme- 

 nites were the first minerals to form. Ilmenite probably was 

 produced in most places because of the presence of iron in the 

 solutions which could combine with the titanium. The brook- 

 ites are found either attached to the matrix, or in analcite, the 

 solution of which on entering the cavity carried away some of 

 the crystals from their slender points of attachment. The 

 ilmenite rosettes and the thick, irregular plates of ilmenite 

 occur close together, and appear to have been produced at the 

 same time. Sometimes there is an acicular, zeolitic mineral 

 (species undetermined) which has grown directly on the ilmenite, 

 and is at times surrounded by the analcite. It is monoclinic, 

 showing pyramid, prism, and macro pinacoid. The analcite 



Am. Jour. Sci.— Fourth Series, Vol. XXXV, No. 208.— April, 1913. 

 31 



