714 PETROLOGICAL ABSTRACTS AND REVIEWS 



and slates. The great majority of the rocks are strongly metamorphosed and 

 in them have been developed sillimanite, corundum, spinel, magnesium-diop- 

 side, scapolite, cordierite, and plagioclase. In this work the various inclusions 

 are petrographically described and several chemical analyses are given. The 

 most abundant inclusions are quartz-sillimanite. 



C. H. BEHRE, JR. 



VoGT, J. H. L. "Die Sulfid-SUikat-Schmelzlosungen," Norsk. 

 Geologisk Tidsskrift, IV (191 7). Pp. 97, figs. 13, and several 

 tables and analyses. 

 VoGT, J. H. L. Die Sulfid-Silikat-Schmelzlbsungen: Die Sulfid- 

 schmelzen und die Sulfid-Silikatschmelzen. Christiania, 19 19. 

 Pp. 131, figs. 45, and numerous tables and analyses. 



The first of these two papers is essentially a resume, written in 191 7, of 

 extensive work on sulphide-silicate solutions, giving the results obtained to the 

 date of its publication. The second paper presents in detail the data of 

 the earlier one, and embraces additional facts gleaned through two more years 

 of work on the same subject; it is more detailed than the earlier publication 

 and will be reviewed here first. The reviewer believes that with such com- 

 prehensive work as this, adequate abstracts are impossible. He strongly 

 advises a careful perusal by metalographers, economic geologists, geochemists, 

 and physical chemists. He wishes to commend the completeness of these 

 studies. 



Previous experiments have shown that certain sulphides, such as SbjSj, 

 BiaSs, and AgzS, have a lower melting point than even those silicates with the 

 lowest melting points. Other sulphides, such as those of lead, copper (CujS), 

 and iron (FeS) and pyrrhotite, have melting points about like those of the 

 least refractory silicates and slightly higher than some of the eutectic mixtures 

 of silicates with I9W melting points. Other sulphides finally, such as those of 

 zinc, manganese, barium, and calcium, have melting points markedly higher 

 than those of the more common natural silicates. Under-cooled sulphide 

 mixtures or solid solutions of sulphides (sulphide glasses) are unknown. 



From a study of the latent heat of fusion it appears that the sulphides PbS, 

 AgjS, CujS, FeS are not highly polymerized. It is found, further, that Fe304 

 is only slightly soluble in melts of CU2S ; this is corroborated by the crystalliza- 

 tion sequence as observed in magmas, for magnetite (and ilmenite) crystallize 

 very early indeed from a pyrrhotite- or pyrite-bearing magma. Silicates are 

 soluble in FeS or CuiS melts to only a very minor degree. 



After a study of the relations between the various sulphides and their 

 eutectics, the writer demonstrates that a eutectic is also possible in solutions of 

 calcium sulphide (or manganese sulphide) in various silicates, such as melilite 



