Geology and Mineralogy. 477 



tricts of the Eastern United States. A detailed study is given 

 of the ore deposits in parts of Halifax, Charlotte and Mecklen- 

 burg Counties, Va., and in Granville and Person Counties in 

 North Carolina. The investigation covers an area of some 550 

 square miles. 



4. Tin Deposits near Irish Creek, Virginia; by Henry G. 

 Ferguson. Pp. 19, with figs. Bulletin XV-A, Virginia Geo- 

 logical Survey, T. L. Watson, Director. Charlottesville, 1918. — 

 This bulletin is important in view of the extreme shortage of 

 tin in the United States at the present time. The author gives 

 an account of the Eockbridge County deposits, which are among 

 the most promising in the country, and concludes "it may be 

 said that the district offers some hope of reward for systematic 

 development of the discovered veins, and a possibility that pros- 

 pecting in the area of hypersthene granodiorite along the Blue 

 Bidge in this vicinity may uncover other deposits. The best 

 indication of a possible tin deposit appears to be the presence of 

 the greisen-like alteration product of the granodiorite, which 

 everywhere appears to accompany the tin-bearing veins. Where 

 float of fragments of this muscovite-fluorite rock is found on the 

 hillsides it should be followed up carefully. Panning of the 

 soil of the hillside may also lead to new discoveries. Areas in 

 which the granodiorite has suffered extensive epidotization will 

 probably be less favorable than those in which the rock is 

 unaltered. ' ' 



5. Neio Mineral Names; by W. E. Ford (communicated — 

 continued from vol. 44, pp. 484-486, December, 1917) : — 



Collbranite. D. F. Higgins, Econ. Geol., 13, 19, 1918. At 

 the Suan mine, Hoi Kol, Korea, in the marble walls of the ore 

 bodies, there occurs a black acicular mineral in stellate aggre- 

 gates. This has been considered as ilvaite, but from microscopic 

 evidence, it is thought to be a highly ferriferous pyroxene of the 

 hedenbergite type. Named after Mr. H. Collbran and his son 

 Mr. A. H. Collbran, who have made the Suan mine a producer. 



Gilpinite. E. S. Larsen and G. V. Brown, Am. Min., 2, 75, 

 1917. Probably monoclinic. In aggregates of minute lath- 

 shaped crystals. Probably tabular parallel to o (010) and 

 elongated parallel to the c axis. Under the microscope shows 

 two sets of twinning lamella?, nearly at right angles to each other. 

 Color pale greenish yellow to canary-yellow. H. = 2. G. > 3-32. 

 Optical axial angle nearly 90°. Dispersion strong. At times 

 optically — with p > v, in other cases -4- with p < v. c paral- 

 lel to elongation and a normal to &( 010). Extinction angle c 

 A c = 5 1/2 — 8°. a = 1-576, j3 = 1-596, y = 1-614. 



Comp. — A hydrous sulphate of uranium and copper. 



EO.UO a .S0 3 .4H,,0 ; B = Cu,Fe.Na 2 . 



Infusible or difficultly fusible but turns black on heating. 

 Beadily soluble in dilute acids. 



