202 Scientific Intelligence. 



base which is assumed to be glass ; whether it may not be wholly 

 or in part analcite is not mentioned. Occasional laths of labra- 

 dorite also occur and in places the rock holds the large masses of 

 olivine often seen in basaltic rocks. An analysis gave the fol- 

 lowing results : 



Si0 2 Ti0 2 A1 2 3 Fe 2 3 FeO CaO MgO Na a O 



43-92 1-78 17-62 4*05 3'94 13-07 8\L6 2-84 



K 2 H 2 S0 3 P 2 5 CI Total 

 1-33 2-82 0-47 0*15 0-32 = 100-37 



This appears to be a well-defined type of this small but interest- 

 ing group of igneous rocks. The name is the translation into 

 Greek of the Siebengebirge where it occurs. l. v. p. 



12. Die Kristallinen Schiefer, I, Allgemeiner Theil, von IT. 

 Grubenmann. Pp. 101, 8vo, 2 pis. 1904, Berlin (Borntrager 

 Pub.) — The author states that this work, which is a summation of 

 his lecture course upon this subject, is an attempt to explain in 

 accordance with physical and chemical principles the origin and 

 characteristic properties of the crystalline schists. He begins 

 with a description of the material from which the schists are 

 formed, giving the origin and characters of the sedimentary and 

 igneous rocks, so far as these pertain to the subject. Next the 

 various factors of metamorphism are dealt with, the effects of 

 solutions, of high temperatures, of pressure, etc. After this the 

 results of these agencies in the production of different minerals, 

 structures, textures, etc., are discussed and the work concludes 

 with a short, general account of the geological occurrence of the 

 crystalline schists. It is clearly and simply written and the stu- 

 dent and teacher of petrography will find much in it that is inter- 

 esting and suggestive. It is inferred from the scope and title of 

 the book that it is only the introductory portion of a larger 

 descriptive work. l. v. p. 



13. Yttrium and Ytterbium in Fluor ite. — W. J. Humphreys, 

 as the result of a spectroscopic examination of samples of fluorite 

 from many localities in all parts of the world, shows that the 

 rare element yttrium is distinctly present in most cases while a 

 considerable number contain also ytterbium. The specimens 

 found to be richest in these elements were from Amelia Court 

 House, Virginia, Llano County, Texas and Corocoro, Bolivia. 

 The two localities first mentioned afford a number of rare mineral 

 species which were also found to contain yttrium and often in 

 addition ytterbium. It is interesting to note that the three 

 samples mentioned proved to be exceptionally sensitive to the 

 effect of heat in producing phosphorescence ; as noted by the 

 author some years since, a fluorite from Amelia Court House 

 became luminous simply from being held in the hand for a few 

 minutes. — Astrophys. Journal, xx, 266. 



14. Hamlinite from Brazil. — The rare mineral species ham- 

 linite, thus far only known from Maine, as described by Penfield, 

 has been identified by Hussak in the diamond-bearing sands of 

 the Serra de Congonhas, Diamantina, Brazil. It occurs sparingly 



