Pirsson — Note on the Occurrence of Astrophyllite. 215 



During the other periods of the day, however, the figures 

 should be little affected by conditions of observation and there 

 seems much reason for reaching the conclusion that the major- 

 ity of meteorites have direct motion and travel at a velocity 

 greater than that of the earth, or 18 miles per second. Here 

 again meteorites differ from meteors, since the larger number 

 of meteors fall in the morning hours. In times of fall by months, 

 days and hours, therefore, the majority of meteorites differ from 

 meteors. Their position in space, orbits and direction of move- 

 ment must, therefore, differ correspondingly also. 



Field Museum of Natural History, 

 December 15, 1909. 



Art. XVI. — Note on the Occurrence of Astrophyllite in the 

 Granite at Quincy, Mass. • by L. V. Pirsson. 



The interesting note of Professor Warren on the finding of 

 a pegmatitic facies of the alkalic granite of Quincy,* and of 

 the minerals it contains, recalls to the writer that he has 

 recently noticed in a specimen of this rock the mineral astro- 

 phyllite. The occurrence is entirely a microscopic one and the 

 crystals are too minute to be detected and tested megascopi- 

 cally, but as the real home of this rare and peculiar species, as 

 shown in the few places in which it has so far been found — 

 Langesund fiord, South Norway ; southern Greenland, and St. 

 Peter's Dome, Colorado — is in the pegmatites of the alkalic 

 rocks, it seems worth while to call attention to the occurrence 

 in order that it may be placed on record, and that attention 

 may be directed to the Quincy pegmatites in the hope of find- 

 ing it in megascopic crystals. This is more especially necessary 

 since from its dark or brownish color and excellent mica- 

 ceous cleavage it is apt to be mistaken for biotite and over- 

 looked. A chemical test for titanium will, however, serve to 

 distinguish it readily from ordinary biotite and zinnwaldite, 

 while lepidomelane, which might be expected in such associa- 

 tions of minerals, rarely contains more than a trace of this ele- 

 ment. In this connection it might be stated that the writer 

 has not observed any of the dark micas in the study of a con- 

 siderable number of sections of the Quincy rock, although 

 Whitef mentions it as occurring at times in minute flakes. 



* This Journal, vol. xxviii, p. 449, Nov. 1909. 



f T. G. White, Petrography of the Boston Basin, Proc. Bost. Soc. Nat. 

 Hist., vol. xxviii, No. 6, p. 131, 1897. 



