MINERALOGY. 545 



Mr. G. F. Kunz has issued in separate form tlie (;liai)t(ir prepared by 

 Liiii, on American Gems and Precious tStones, Toi- Uic, MiiK^ral ItesoiirceH 

 of the United States of Mr. A. Willianhs. A pojiular volume, entitled 

 Leisure Hours Among the Gems, has ai)])eared from the pen of Mr. A. 

 C. Ilamlin. Dr. Fletehei-'H Guide to the Mineral Gallery of the British 

 Museum, with an iiitiodiiction to tlie .study of minerals, is a work of 

 some interest even to those who are not so fortunate as to have the op- 

 ])ortunity to study tlie beautiful eollcclion of minerals at South Ken- 

 sington. 



CRYSTALLOGRAPHY AND PHYSICAL MINERALOGY. 



Many contributions have been made to our knowledge of tluj (crystal- 

 line form of different mineral species, and numerous additions have been 

 made to the already long lists oi" known i)laneH. Only a few memoirs 

 of more than ordinary 8Coi)e and interest will be mentioned. Two ex- 

 fended articles on this branch of mineralogy have been published by 

 II. A. Mieps, of the British Museum. One of these {Min. Mag., v, .'325) 

 is devoted to the descrI])tion of crystals of iiH;n(!ghinite ftom Bottino, 

 near Serravezza, in Tuscany. The same subji-cf was a little earlier dis- 

 cussed by Krenner, inthe Proceedings of the Hungarian Geological 

 Society. The results of the two investigations agree closely, they i)ro\'e 

 that the species is to ])e iclerred to the orfhorhombic; system; not mon- 

 oclinic, as has been hitherto assumed. The crystals are highly comi)lex 

 in form. A second paper by Miers is a moiU)graph of the species 

 l)ournonite [Ih., vi, ]>. 5<)), in whi(;h IIm; author re\i(;ws the work of earlier 

 crystallographers, Irom the time of Bournon (1804) down. To the list 

 of 50 forms already identified, Miers adds twenty-nine nccw on(;s, deter- 

 mined beyond doubt, and twenty-one others, which are of jare> occur- 

 rence and need confirmation. Miers accepts the eh^ments of Miller 

 (1852), and from these calculates a list of upwards of one thousand an- 

 gles, being the angles between the normals of all the known planes and 

 the most important planes of reference;. The memoir is accomj)ani(;d by 

 two plates, with num<irous figures, and a si)herical proje(;tion. 



Another monograph is by W. J. Lewis, of Cambridge, on miargyrife 

 {Zeitsch. Kryst., viii, 545), which adds much to our knowledge, of the com- 

 I)lex crystals of that rare species, and removes some donbtfid jioints 

 about them. The paper contains a large number of figures and a long 

 list of measured angles compared with the angles calculated from the 

 accepted elements. A pai)er by Max Schuster (Min. Petr. Mitth., vi, 

 301), on the structure and character of the crystalline surfaces of the 

 Swiss danburite, certainly leaves nothing unsaid on that subject. It 

 covers upwards of two hundred ])ages, and is the second part of a 

 memoir, the first of which was published a year ago. The detailed 

 description of the vicinal i)romiuences on the planes, and all the other 

 peculiarities, especially in their infliu'uce upon the; int(;r- facial angles 

 HKiasured with flu; refle(;ting goni)neter, is not without ijit<;rest, but the 

 S. Mis. ;« 35 



