MINERALOGY. 690 



<,aeeii ; tianspareut. The optic axes lie iu a plane parallel to the brachy- 

 pinacoid, and the bisectrix is negative and normal to the basal x)laue 5 

 the axial angle is large, 80° for green rays, measured in a solution of 

 mercuric iodide in potassium iodide (m = 1'722). The pleochroism is 

 distinct. An analysis yielded the following results: 



N2O5 CuO H2O 



22-76 66-38 11 26 =100-40 



The formula calculated, viz, 4CuO, NjOs, 3H2O, requires N2O5 22-52, 

 CuO 6G'22, H2O 11'56 = 100, agreeing closely with the results of analy- 

 sis. The mineral is named after the chemist who first determined the 

 true composition of the corresponding artificial compound. This arti- 

 ficial salt, as noted on a previous page, has also been made by Wells 

 and Penfield and shown to crystallize in the monoclinic system ; the form, 

 however, is rather closely related to that of the orthorhombic geihard- 

 tite. 



Grcvphitoid. — This name has been given by Sauer to a substance whicli 

 he regards as amorphous carbon. It occurs extensively in the mica 

 schists and phyllites of the 8axon Erzgebirge. It forms loose incrusta- 

 tions on the surfaces of the schist, shows no crystalline structure, and 

 burns with comparative rapidity in a Bunsen burner. An analysis of 

 the combustible substance gave — carbon, 99-76; hydrogen, 0-24 = 100; 

 showing that it is essentially pure carbon. Besides occurring as an in- 

 crustation it also impregnates the rock mass, forming fine bands of mi- 

 nute particles passing iu parallel directions through the irregular quartz 

 grains. The author recognizes the fact that true graphite is also a 

 common constituent of many archsean rocks, but suggests that with it 

 the graphitoid may also be present. A related form of amorphous car- 

 bon was described a few years ago by von Inostranzeff, also from phyl- 

 lite. 



Hatiksite. — A new anhydrous sulphato-carbonate of sodium, described 

 by W. E. Hidden, obtained from San Bernardino County, California, 

 where it occurs with thenardite, borax, &c. It is named after Mr. 

 Henry G. Hanks, State mineralogist of California. Hanksite crystallizes 

 in the hexagonal system, the crystals being short hexagonal prisms 

 with one or two pyramids and the basal i)lane ; they sometimes form 

 confused groups of tabular six-sided crystals. Optically it is uniaxial, 

 negative. The hardness is 3 — 3-5, and the sj^ecific gravity 2-562. The 

 color is white, inclining to yellow; the crystals nearly transparent, 

 though sometimes inclosing impurities. An analysis by J. B. Mackin- 

 tosh gave the results under I, below ; another analysis by S. L. Penfield, 

 made two years since upon a large crystal from California (exact locality 

 unknown), is given under II. 



S0» CO3 01 Na20 



1 45-89 5-42 2-36 4634= 10001 



II 43-59 5-42 2-13 40 86 K 233, insoL 4 41, igu. 1^2 ~ 10006 



