670 SCIENTIFIC RECORD FOR 1883. 



Wien, November, 1883) upon the scapolite group, which may be taken 

 as a companion to Ihe earlier memoirs by the same author upon the 

 feldspars and upon the mica group. The subject of the scapolites is a 

 peculiarly difficult one, since there is the wide variation of composition 

 but without a corresponding variation in crystallographic or optical 

 properties such as characterizes the members of the feldspar group. 

 Tschermak's work is based largely upon new analyses made with 

 especial care to insure the highest possible degree of accuracy. His 

 method is essentially that which has served to throw so much light 

 upon the feldspars, namely, to explain all the varying compounds as 

 isomorphous mixtures of two end silicates. In the case of the feldspars 

 the two extremes of the series have a real existence, and hence the 

 theory rests upon fact, in the case of the scapolite hypothesis plays a 

 more prominent part, and hence the system is to some extent artificial. 

 The two fundamental silicates assumed as fundamental among the 

 scapolites are the meionite silicate Si 12 Al 12 Ca 8 O 50 and marialite silicate 

 Si 18 Al 6 Na 8 48 Cl 2 , and all the others are regarded as intermediate 

 isomorphous mixtures of these two extremes in different proportions. 



Among the many more papers which might be referred to, can be 

 mentioned a few by title only, as the dissertation by McCay upon the 

 arsenides of iron and cobalt (Freiberg) ; a paper by Heddle ( Trans. Boy. 

 iSoc. Edinburgh, xxx) upon the ores of iron, manganese, titanium, &c, 

 in Scotland ; the papers on the cryolite group alluded to on an earlier 

 page; a paper by Penfield (Amer. Jour. Sc, xxvi, 361) on a peculiar 

 massive variety of descloizite (near tritochorite of Frenzel) from Mexico; 

 a paper containing analyses of zeolites from Zritz, Pennsylvania, by 

 Sadtler (Amer. Chem. Journ., iv, 356), and another by E. F. Smith (lb., 

 V, 272), on minerals from Lehigh County, Pennsylvania, and by D. B. 

 Brunner (lb., v, 279) and E. F. Smith, on the composition of some min- 

 erals from Berks County, Pennsylvania. 



OCCURRENCE OF MINERALS, ESPECIALLY IN THE UNITED STATES. 



The State of Maine, always remarkable for the fine and rare minerals 

 it has afforded, has had several interesting localities added to its already 

 long list. At Stoneham, in Oxford County, Mr. Nathan W. Perry dis- 

 covered a fine topaz locality. Subsequent work there by himself and 

 by Mr. George F. Kuuz has brought to light some very remarkable 

 specimens. The finest topaz crystal, in beauty of appearance and com- 

 plexity of form, is worthy of being ranked with the fine topaz crystals 

 from Siberia. The locality at Stoneham (briefly alluded to in the Be- 

 port for 1882) was described by Mr. Kuuz at the Minneapolis meeting 

 of the American Association for the Advancement of Science. The 

 topaz crystals occur in pockets in the albite. They vary in size from 

 the smaller ones, which are nearly transparent and of a white or faint 

 green or blue color, to very large, coarse crystals, or fragments of 

 crystals, weighing more than 40 pounds. An analysis by Mr. C. M. 



