MINERALOGY. 459 



to the already long catalogue for the two species, and others that are 

 not certain. He also distinguishes between the characteristic forms of 

 pyrargyrite and proustite, not often attempted before, and develops 

 the hemimorphic nature of the two species. 



A study of some specimens of polianite from Flatten, IJohemia,' has 

 led to the interesting conclusion that the anhydrous MnO., crystallizes in 

 the tetragonal system and is isomori)hous with rutile (TiO^) cassiterite 

 (Sn02) and zircon (SiOi, ZrO-^). The fact that the hard, gray manganese 

 ore, polianite, was distinct from the soft pyrolnsite was long ago insisted 

 upon by Breithaupt, and his view is thus fully sustained. Flint has 

 extended his earlier crystallogra{)hic studies and has given valuabl<i 

 contributions on scolecite, brauuite, hausmannite, and other species 

 from Sweden. The crystals of rutile,- apatite, and beryl, of Alexander 

 County, North Carolina, are described by Hidden and Washington and 

 shown to have a number of interesting features. Some of the species of 

 the chrysolite groui) have been studied by Bauer ' and the relation be- 

 tween their forms and composition brought out. The species especially 

 considered are chrysolite, hyalosiderite, and the magnesium silicate 

 forsterite. Crystals of kaolinite,^ rarely obtained iu a form allowing of 

 study, have been described by Allan Dick and their form measured and 

 figured by H. Miers. A mouoclinic parameter is assigned to them, viz : 



a : b : r : = 0.5748 : 1 : 4.72r)7: //=83o 11' 



The kaolinite from Colorado'^ was recently referred to the triciinic 

 system of Keusch on the basis of an optical examination. The subject 

 of the crystallization of ullmannite has been reviewed by Klein," and it 

 is shown that both kinds crystallizing in the pyritohedral and tetrahe- 

 dral divisions of the isometric system are identical in composition, as 

 proved by analyses by Jannasch. An inaugural address by Herschenz 

 gives an account of the Harz barite, with a number of new foinis. Dii- 

 sing" adds many other new planes for crystals of various localities; 

 many of them seem to be vicinal planes. The inexhaustible sp**cies 

 epidote has been taken up anew, the Swedish mineral by Flink," that 

 from the Austrian Alps by Griinzer,-' and again by Zimanyi,"' and that 

 from Elba" by Artini. The result of these memoirs is to add a number 

 of new forms to the already very long list. The absorption phenomena of 

 epidote have been studied by Bamsay.'^ Be(;ke'-' continues a foitner line 

 of investigation iu describing the etching figures on pyrite, si)]ialerite, 



'Amer. Journ. Sci., 1888, vol. xxxv, i «Bih. Svcusk.Vet. Ak. Hand!., vol. xii, 

 243. pt. 2. 



'^Ibid., 1887, vol. xwiiup.rm . ] ''Mem. Accad. Lincie, 1887, vol. iv, 



sjahrb. Miu., 1887, vol. i, 1. i NovemlR-r 13. 



"Mill. Mug., 1888, vol. viii, p. 15. I '"Miii. pclr. Mittli., voi. ix, :5(il. 

 Mahib. Mill., 1887, vol. ii, 7U. " Foldtani Kozloiiy, vol. x viii, 443. 



^Ibid., 1G9. ! '-Zeitschr. Kryst., voi. xiii, 97. 

 'Zeitschr. Kryst., vol.xiv, 4bl. 'iMIn. lutr. Miltli.. vol.ix. p. I. 



