Ford, Ward and Pogue — Mineral Notes. 187 



16*3)= 24° 42' and 24° 48 / agreeing closely with the calculated 

 value of 24° 46'. This pyramid was first noted by vom Bath* 

 on crystals from Andreasberg in the Harz ; and has been noted 

 on crystals from Union Springs, Cayuga County, N". Y., by 

 Penfield and Ford,f but never so far, as the writers know, has 

 it been found so largely and simply developed, as in this 

 instance. The crystals are honey-yellow in color, and average 

 from 3 to 4 cm in length and from 1 to l'5 cm in greatest 

 diameter. 



3. Crystals of Datolite from Bergen Hill, N. J.; by W. E. 

 Ford and J. L. Pogue. 



A short time ago Prof. E. S. Dana received from Mr. James 

 G. Manchester of New York City a small snite of unusally 

 perfect and symmetrical datolite crystals, which being shown 

 to the present writers seemed worthy of a brief description. 

 They were found lying loose in sandy material at the bottom 

 of the open cnt which is at present being put through the trap 

 ridge at Bergen Hill by the Erie railroad. Most of the crys- 

 tals were completely and symmetrically developed, and showed 

 no evidence of previous attachment to other minerals or a rock 

 surface. In one specimen the small crystals of datolite were 

 seen lying in the angles between interpenetrating rhombohe- 

 drons of calcite, and in another they were associated with an 

 asbestiform mineral and minute crystals of apophyllite.' The 

 crystals were all of them small, the largest of the suite shown 

 in its true proportion and development in figure 4 being 8 mm 

 in its greatest diameter. Many of the crystals were much 

 smaller. They are colorless, perfectly transparent, and their 

 faces have a brilliant luster. But of chief interest is the 

 almost ideally symmetrical development which they possess, a 

 thing of considerable rarity among datolite crystals. The 

 forms identified, all of which are common, were as follows : 

 a (100), c (001), m (110), m x (011), IF (114), A (112), 7(111). 



Mineralogical Laboratory of the Sheffield Scientific School of 

 Yale University, New Haven, Conn., July 1, 1909. 



*Pogg. Annalen, cxxxii, p. 521, 1867. f This Journal, x, 237, 1900. 



