Geology and Mineralogy. 399 



lowing paragraphs from the introduction : " There was a decrease 

 in the production of precious stones in the United States during 

 1910, though the output of such matrix gems as turquoise and 

 variscite was still large. Nearly 8^ tons of rough turquoise were 

 produced in 1910, as compared with more than 17 tons in 1909, 

 and more than 2^ tons of rough variscite, as compared with 3| 

 tons in the preceding year. New deposits of both these minerals 

 were found in Nevada and a very promising deposit of variscite 

 was developed near Lucin, Utah. New deposits of californite 

 were discovered in California, and a white garnet scarcely to he 

 distinguished from the white vesuvianite variety of californite 

 was found in quantity in Siskiyou County, Cal. This mineral is 

 with difficulty distinguished from white jade, for which it could 

 well be substituted. 



The output of tourmaline was considerably less in 1910 than in 

 1909, but a new deposit of fine gems and specimens of tourmaline 

 was opened in Maine. The aquamarine deposit on Mount Antero, 

 Colo., yielded a quantity of good gem material along with crys- 

 tals of associated minerals, as phenacite, colorless and smoky 

 quartz, etc. The development of the new emerald prospect in 

 North Carolina was limited and met with only partial success. 

 More recent work during 1911 has resulted in finds of better 

 promise. The presence of valuable gem material has been proved, 

 but the quantity of gems to be expected from the vein is still a 

 matter of doubt. Further prospecting and dredge mining for the 

 variegated sapphires of Montana were carried on, but the princi- 

 pal value of the sapphire production came, as usual, from the 

 deposits of blue sapphire in Fergus County." 



8. The Crystalline Symmetry of the Diamond. — The true 

 symmetry of the diamond has often been questioned, and some 

 authors have been inclined to refer it to a class of low symmetry, 

 that of the tetrahedrite type. A monograph on this subject has 

 recently been published by A. L. W. E. van deb Veen as an 

 inaugural dissertation at the University of Delft. The author 

 has investigated the subject from the physical as well ascrystallo- 

 graphic side, basing his observations particularly on the Molen- 

 graaff collection. His conclusion is stated with much confidence 

 that the species really belongs to the holosymmetric class, the 

 hexoctahednd class of Groth. 



9. Hock Minerals : Their Chemical and Physical Characters 

 and their Determinatio)i in Thin Sections • by J. P. Iddings. 

 Second Edition, revised and enlarged. Pp. 617. New York, 1911 

 (John Wile}' & Sons). — The first edition of this valuable book was 

 published in 1906 and numbered 548 pages. The present edition 

 has been enlarged to 617 pages, chiefly through the addition of 

 the descriptions of more than sixty rarer species which were 

 not included in the earlier edition. The optical tables at 

 the end of the book have been somewhat enlarged and a bire- 

 fringence diagram added. w. e. p. 



