ean Naturalist. 



tephrite of Eulenberg in Bohemia, pronounced by Zepharovich 1 to be 

 orthoclase, has been carefully investigated by Griinzer, 2 who thinks it 

 more likely to be a zeolite. Its crvstahzation is probably tnclinw. 

 though by the parallel growth of many individuals there is built up a 

 form closely resembling that of orthoclase. — The minerals characterizing 

 the hollow spherulites of the rhylit,- of ( Hade Creek/ Wyoming, and 

 of Obsidian Cliff, in the Yellowstone National Park, like those found 

 in other lithophysre, are thought to be the results of aqueo-igneous 

 fusion upon the material of the acid lava. The most abundant mineral 

 thus formed is quartz, whose crystals are either attached to the walls of the 

 cavities, thus exposing only one termination, or are interlaced forming 

 a network built up of crystals occasionally doubly-terminated. Both 

 the rare -f f R and — f R are well developed, and also the equally 

 rare forms ±f Pi. The next most noticeable mineral mfayalite, whose 

 habit has already 4 been described. In some of the more irregular 

 cavities at (Hade Creek are accumulations of very small sanidine crys- 

 tals, hornblende and biotite, of which the latter is never found associated 

 with fayalite.— The rhodizite from the Urals, which has been declared 

 to be regular with oo aud 2 , is pyroelectric. The examination of it, 

 extinction and its interference colors shows it to be pseudosymmetrical 

 it being in reality monoclinic 5 with a : b: c:=.707 : 1 : 1. /3=90°. The 

 dodecahedron becomes OP,— P, -fP and oo Poo" and the tetrahedron 

 ±0, P55- and oo P 2\ An interesting series of experiments made by the 

 same mineralogist on jeremejewite lately described by Websky 6 shows it 

 to consist of an interior hexagonal kernel, surrounded by two zones with 

 some orthorhombic properties, and an external one, with the charac- 

 teristics of the kernel. The density of the material in each zone is the 

 same, and its reaction under pressure and temperature is similarly 

 slight. The kernel and the peripheral zones are uniaxial and negative, 

 while the other two zones are biaxial, the inner one possessing the lar- 

 ger optical angle. The explanation of the phenomena offered by the 

 author is to the effect that in the first stage of the mineral's growth it 

 separated as an orthorhombic substance on the walls of the cavity- 

 Upon this were deposited zones two and three, after which the cavity was 

 filled by what is now the kernel. The optical anomalies of phacolite 





