ZIRCONIFEROUS SANDSTONE NEAR ASHLAND, VIRGINIA 287 



In the investigation of the black sands of the Pacific slope* by the 

 Federal Survey zircon was rejiorted to be the fifth most abundant constitu- 

 ent in a long list of minerals found. 



Metamorphic rocks. Zircon has been reported in nearly all classes of 

 metamorphic crystalline rocks, especially in the feldspar-rich gneisses of 

 probably igneous origin, and in the different types of crystalline schists, 

 particularly the hornblendic,t chloritic and micaceous groups. It is 

 usually present in varying amounts in the quartzites| examined. Van 

 Hise§ reports zircon as especially common in marble, and Clarke T| remarks 

 that it occurs in some limestones in contact positions. According to Hoff- 

 mann" reddish-brown crystals of zircon, sometimes a half inch in diameter, 

 occur in abundance in crystalline limestones of the township of Grenville 

 (Argenteuil County), Canada, associated with wollastonite, pyroxene, 

 sphene, graphite, etc. It occurs in small amount in some slates and 

 phyllites. 



Iron (magnetite ores) . Zircon has been noted as an accessory mineral in 

 iron-ore deposits, especially those of magnetite, in many localities, more 

 particularly iii New York, New Jersey, Pennsylvania, and the Unaka 

 Mountains of North Carolina and Tennessee, and at Orendal, Norway. 

 Blake o reported the occurrence of zircon in considerable quantity in the 

 magnetite ores of the Rees and Wilder tract, Unaka Mountains of east 

 Tennessee and North Carolina. The zircons were described as dark red- 

 brown crystals ranging in size from one-tenth of an inch and less, to five- 

 tenths of an inch in length. 



Zircon occurs in the magnetite ores of New Jersey near Franklin Fur- 

 nace. Palache|| says that some of the minerals associated with zircon 



* Mineral Resources of Ike United States, Calendar Year 1905, pp. 1175-1258. 

 Mineralogical examination of tliese sands at various localities along the Pacific slope 

 has been made by various students, dating back as early as 1853. See Blake, W. P., 

 Atner. Jour. Sci., 1854, vol. 18, p. 156. 



t Derby, O. A., On the Separation and Study of the Heavy Accessories of Rocks, 

 Proc. Rochester Acad. Sci., 1891, vol. i, pp. 198-206. 



t Thiirach, H., Op. cit. 

 Trueman, J. D., Jour, of Geology, 1912, vol. xx, pp. 244-257. 



§ Van Hise, C. R., Op. cit., p. 315. 



H Clarke, F. W., Op. cit., p. 678. 



" Hoffmann, G. Ch., Oeol. and Nat. Hist. Surv. of Canada, 1888-89, vol. iv, p. 

 66T. 



G Blake, W. P., Note on Zircons in Unaka Magnetite, Trans. Amer. Inst. Min. 

 Engrs., 1879, vol. vii, p. 76. 



II Palache, C, Folio 161, U. S. Geol. Survey, pp. 8-10. 



