Geology and Mineralogy. 367 



appear in normal position. By thus considering the various solu- 

 bilities of the different minerals in one another, the solvent 

 action of contained water, and rises of temperature and resolution 

 occasioned by successive crystallization, he is able to devise a 

 scheme which will account for abnormalities in the order of 

 appearance. In connection with this the reviewer would point 

 out that it has scarcely been shown as yet that hornblende, as such, 

 can exist in the molten solution ; the trend of investigation, indeed, 

 tends to prove that the mineral molecules existent in the magma 

 are of much simpler composition, and it seems probable that 

 hornblende comes into being only in the act of crystallization. — 

 Trans. Edinb. Geol. JSoc, ix, pt. iv, 247, 1909. l. v. p. 



5. New Occurrence of Lujavrite. — The very rare and remark- 

 able rock lujavrite was first found and named by W. Ramsay, 

 from its occurrence at Lujavr Urt in the Kola Peninsula, Rus- 

 sian Lapland. It has been subsequently described by Ussing 

 from southern Greenland. A new locality is now announced by 

 H. A. Beouwee from Pilandsberg in the Transvaal. Like the two 

 former occurrences, it consists of very flattened alkalic feldspars 

 intermingled with nephelite and eudialyte and is pegged through 

 with acicular aegirite. It also contains the associated rare min- 

 erals astrophyllite, mosandrite and lavenite. The eudialyte is 

 apt to be changed into catapleiite, while considerable quantities of 

 secondary pectolite are present. The following analyses of two 

 varieties of the rock are by F. Pisani : 



Si0 2 Ti0 2 Zr0 2 A1 2 3 Fe 2 3 FeO MgO CaO Na 2 K 2 H 2 

 I 52-35 0-59 0-39 1411 7'98 2-17 0-66 4-65 9*30 2*78 3-20 



= 100-30 

 II 51-35 2-75 0-54 11*45 9-40 2-41 054 3*27 10-80 2'52 3'20 



= 99-48 



The total includes in I, MnO = 0*62 and CO 2 =T50; in II, 

 MnO = 1 -25. These correspond closely with the analyses of the 

 Kola and Greenland rocks. It maybe also mentioned that rocks 

 resembling lujavrite have been described by Lacroix as a marginal 

 facies of nephelite syenite from the Los Islands, French Guinea. 

 The association with nephelite syenites occurs also with the 

 lujavrites previously mentioned. — Comptes Rendus, Nov. 29, 1909. 



l. v. P. 



6. The Mercury Minerals from Terlingua, Texas. — The 

 remarkable minerals from Terlingua, several of them new, were 

 described by Moses in 1903 (this Journal, vol. xvi, 253) ; later a 

 preliminary account of their chemical examination was given by 

 Hillebraxd and Schaller (vol. xxiv, 259, 1907). The latter 

 authors have now published their complete results in Bulletin 

 405 of the U. S. Geographical Survey. Many points of interest 

 are brought out, particularly the remarkable complexity of the 

 crystallization of the new species : thus montroydite is shown to 

 have 56 forms, terlinguaite 134 forms, and even the isometric 

 esrlestonite 20 forms. 



