MINERALOGY. 545 



Mr. G. F. KuDz has issued in separate form the cliapter i)rei)aied by 

 him, on American Gems and Preeioun tStones, for tlje Mineral llesources 

 of the United States of Mr. A. Williams. A i)oi)ular volume, entitled 

 Leisure Hours Among the Oems, has appeared from the pen of Mr. A. 

 C. Hamlin. Dr. Fletcher's Guide to the Mineral Gallery of the British 

 Museum, with an introduction to the study of minerals, is a work of 

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

 portunity to study the beautiful collection of minerals at South Ken- 

 sington. 



CRYSTALLOGRAPHY AND PHYSICAL MINERALOGY^ 



Many contributions have been made to our knowledge of the crystal- 

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

 made to the already long- lists of known planes. Only a few memoirs 

 of more than ordinary scope and interest will be mentioned. Two ex- 

 tended 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 description of crystals of meneghinite Irom Bottino, 

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

 cussed by Krenner, in the Proceedings of the Hungarian Geological 

 Society. The results of the two investigations agree closel^^ they prove 

 that the species is to be referred to the orthorhombic system; not mon- 

 o(;linic, as has been hitherto assumed. The crystals are highly complex 

 in form. A second paper by Miers is a monograph of the species 

 bournonite (76., VI, p. 50), in which the author reviews the work of earlier 

 crystallographers, from the time of Bournou (1804) down. To the list 

 of 50 forms already identified, Miers adds twenty -nine new ones, deter- 

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

 rence and need confirmation. Miers accex)ts the elements 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 accompanied by 

 two plates, with numerous figures, and a si^herical projection. 



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

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

 plex crystals of that rare species, and removes some doubtful ])oints 

 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. Miith., 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 pages, and is the second part of a 

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

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

 peculiarities, especially in their influence upon the inter-lacial angles 

 measured with the reliecting goiiimeter, is not without interest, but the 

 S. Mis. 33 35 



