256 H. Hies — Artificial Crystals of Zinc Oxide. 



Art. XXXV.— Note 



on Artificial Crystals of Zinc Oxide ; 

 by Helnrich Ries. 



The occurrence of artificial crystals of zinc oxide in the 

 reverberatory furnaces used in the manufacture of zinc white 

 is not uncommon, but the crystals are usually rounded and 

 their faces give poor reflections. 



A number of good crystals have been described by foreign 

 mineralogists,* but the only notice of those occurring in Amer- 

 ican furnaces is by G. A. Koenig,f who notes some crystals of 

 artificial zinc oxide from the furnaces at La Salle, 111. The 

 needle-like character of the crystals, and their apparent hexag- 

 onal habit is commented on, but no measurements were made 

 of them. 



The writer recently received two lots of these crystals, one 

 from Mr. D. A. van Ingen of the New Jersey Zinc and Iron 

 Co., in Newark, N. J., and the other from Mr. Gr. F. Kunz 

 who collected them at the works of the Passaic Zinc Co., in 

 Jersey City, N. J. The crystals from Newark showed com- 

 binations of pyramid and prism, but the faces gave too poor 

 reflections to permit identification. Among the lot from Jer- 

 sey City were several crystals whose faces gave fairly satis- 

 factory measurements. The following combinations were 

 observed : 



A first order prism and first order pyra- 

 mid f ; a first order prism and first order 

 pyramid ■§ ; a first order prism m, and sec- 

 ond order pyramid e, |— 2. This last crystal 

 was doubly terminated and holohedrai. 

 Second order pyramids are not common, 

 and the writer has not seen the face e pre- 

 viously noted. 



Both the natural and artificial zinc oxide 

 are said to be hemimorphic in habit,:}: but 

 none of the specimens examined could be 

 said to have this habit. One crystal showed 

 a tapering prism, low pyramid, and base. 

 The crystals were colorless, transparent and without basal 



*Koch: Beitr. z. Kenntniss Kryst. Huttenprod. ; Gottingen, 1822. Des 

 Cloiseaux: Aim. d. Mines, 1842 (4), vol. i, p. 488. Levy, Ann. Mines, iv, p. 516, 

 1843. G. v. Rath: Pogg. Ann. 1864, vol. 122, r>. 406 and 1871, vol. 144, p. 580. 

 A. Firket: Ann. Soc. Geol. Belg. 1885, 12th Bull, p. 191. G. Greim: Ber. d. 

 Oberhess. Ges. f. Nat. u. Heilk., 1886, vol. xxiv, p. 51. K. Busz: Zeitschr. f. 

 Kryst. u. Min. 1888-1889, vol. xv. J. T. Cundall: Min. Mag., vol. ix, no. 41, 

 1890. A. Hutchinson: Ibid., vol. ix, p. 5, 1890. 



f Proc. Phila. Acad. Sci., 1873, p. 12. 



JDana, System of Mineralogy, 1892. p. 208. 



