392 



Armstrong — Zircon as Criterion of 



sand grains ; some of the coarser sandstones yield zircons 

 which under the high power show sharp-edged and lus- 

 trous faces. It is in highly zirconiferous sandstones, 



Figs. 1 to 9. 



SZ 



Figs. 1, 2, 3. — Typical water -worn zircons from zirconiferous sands, Pablo 

 Beach, Florida. 



Fig. 4. — Deformed zircon, showing single secondary crystal face; from the 

 Stony Creek gneiss (igneous), Connecticut. 



Figs. 5-8. — Zircons from Stony Creek gneiss; all are covered with blistery 

 growth and show small secondary faces. 



Fig. 9. — Rounded zircons in a normal, undeformed granite; Norcross 

 quarry, Stony Creek, Conn. 



such as those described by Watson and Hess, 3 which are 

 evidently the result of repeated re-concentration, that the 

 rounding is most highly developed and gives rise to 

 shapes characteristic of water-worn grains, such as flat- 



T. L. Watson and F. L. Hess, Univ. of Virginia Phil. Soc, July, 1912. 



