406 Scientific Intelligence. 



Hull, F.R.S., Director of the Geological Survey of Ireland. 

 18 pp., 12mo, with an illustrative diagram. London, 1887 

 (C. W. Deacon & Co.). — This work is a very brief sketch of 

 geological history, giving the chief facts in small compass, with- 

 out illustrations. 



8. The so-called Harlem Indicolite ; by R. B. Riggs. (Com- 

 municated.) — Some time since a peculiarly bright blue mineral, 

 found at Harlem, N. Y., was sent to the National Museum by 

 Mr. H. D. M. Fair, of Sing Sing, N. Y., for identification. It 

 occurs in slight columnar crystals, in a quartz-feldspar rock 

 abounding in the more or less disintegrated quartz. Is infusible, 

 but loses color on being ignited. It is of rare occurrence and 

 material sufficient for analysis was not at first to be had. The 

 finding of boric acid, however, leads to the conclusion that the 

 mineral was a rare variety of tourmaline. In studying the tour- 

 maline my attention was called to it, and thinking that a partial 

 analysis, at least, might be desirable, something over a gram of 

 quite pure material was finally obtained. The analysis, as follows, 

 at once revealed relations very different from those existing in 

 tourmaline : 



Si0 2 B 2 3 * A1 2 3 MgO Na 2 K 2 lgn. 



34-82 4-07 55-30 0'57 1-76 1 -04 2-96, Fe 2 3 , CaO, Li 2 tr. — 100-52 

 Eatio -580 -058 -054 -029 -011 -165 



Through the kindness of Mr. G. F. Kunz additional material, 

 sufficient tor certain determinations made in duplicate, was ob- 

 tained. The molecular ratios, deduced from the analysis, are 

 very closely expressed by the formula 



3(H 2 0) . (Na, K),0 . lO(Al 9 0,) . 10(SiO 2 )B 2 O 3 



a new boro-silicate. The question of the purity of material 

 analyzed is ever an important one. From the nature of the case 

 it is probable that we have something new to deal with. Impuri- 

 ties coming from either the associated quartz or feldspar would 

 tend to increase the silica and lower the alumina ratios, and that 

 very materially. 



That this blue mineral is not tourmaline was also made evident 

 by the microscopic study very kindly made by Mr. J. S. Diller, 

 who, with but little material at his disposal, was nevertheless able 

 to make the following observations. " It is undoubtedly biaxial 

 with remarkable pleochroism, (c) ultra-marine, (b) reddish violet, 

 (a) colorless. The angle of extinction is very small, the largest 

 observed being 8°. Its structure is sub-fibrous, so as to render 

 somewhat obscure the angle of prismatic cleavage." 



That this so-called indicolite is not such is certain, that it is a 

 new boro-silicate is highly probable. 



Chem. Lab. U. S. G. S., Washington, Aug. 31, 1887. 



9. Notes on some Mineral localities in Litchfield, Conn. ; by 

 M. R. Gaines. — The following observations on the occurrence of 

 washingtonite " in place " in the town of Litchfield, Conn., w r ere 



* Mean of two determinations 3'83, 4 - 31. 



