418 Journal of Applied Microscopy. 



and that at right angles thereto by q, it was found that the ratio y decreased 

 steadily with an increasing temperature, that is, the value of / increased more 

 rapidly than that of q, so that the spots, which after thirty-five minutes at 105 

 degrees were slightly longer in the direction q, ('[ ~ 1.180), became after ten 

 minutes at ll'i to 118 degrees slightly longer in the direction /, (y = .882), and 

 after only one minute at 100 degrees were much longer in direction /, {— — 0.667). 

 The stripes are about 'L~ to 8 degrees from parallelism to the conchoidal 

 fracture, and make an angle of about 39 degrees with one diagonal, and \'l 

 degrees with the other ; the direction at 42 degrees to the stripes is approximately 

 the direction of greatest thermal expansion in the cleavage plane. a. j. m. 



INDIVIDUAL SPECIES. 



Andalusit, Ueber den, vom Montavon in Vorarlberg. H. Gembock. Neues Jahib. f. Min. 

 2: 89-98, 1898. 



Baddeckite. A new variety of Muscovite. G. H^ (Ca, Mg, K.,, Na2) (FCg AU).^ 

 C. Hoffmann. Am. Jour. Sci., 4, 6: 274, g- q ^ hydro-muscovite, with the 



1898. 8 28 .7 _ ' 



usual proportion of alumma replaced 

 by ferric oxide. Occurs near Baddeck, Nova Scotia, in copper-red scales, which 

 fuse to shiny black slag, and finally become magnetic. G. ^3.252. Decomposed 

 by strong hydrochloric acid. l. McI. l. 



Brookits, Umwandlung und secundiire Zwilhingsbildung des, vom Rio Cipn, Brasilien. E. 

 Hussack. Neues Jahrb. f. Min. 2: 99-101, 1898. 



Corundum. On the origin of, associated with Author agrees with other investigators 

 the Peridotites in North CaroUna. J. H. jj^ regarding the peridotites as Plutonic 

 Pratt. Am. Jour. Sci., 4, 6: 49, 1898. ^ ° ^ ^ 



igneous rocks, and considers the cor- 

 undum to have formed at the same time as the dunite, being held in solution by 

 the molten mass of the dunite, and crystallizing out among the first minerals as 

 the mass began to cool. The corundum is associated with clinochlor. Many 

 field evidences cited by author in drawing his conclusions, as well as results of 

 experiments on solubility of alumina in molten basic glass, with separating out of 

 corundum and spinel crystals on cooling. l. inicI. l. 



Forms of crystals of this rare mineral 

 Diaphorite from Montana and Mexico. L. J. 1 1 r ^1 i iv t ^ 



Spencer. Am. Jour. Sci., 4, 6 : 316, 1898. recorded for these localities. Interest- 

 ing morphotropic relation given be- 

 tween andorite, diaphorite, and freieslebenite, which suggests that the composi- 

 tion may also be proved to fall between that of andorite and freieslebenite. 



L. McI. L. 



Erionite, a new Zeolite. A. S. Eakle. Am. Found on milky opal as tufts of snow- 

 Jour. Sci., 4,6: 66, 1898. , ., ,, ., 1 .1 

 ■' ' ^' ^ white, woolly threads ; or compactly 



matted in fissures. Lustre pearly. Fuses easily and quietly to clear, colorless 

 glass. Yields much water. Soluble with great diflficulty in hydrochloric acid. 

 G.=1.907. Composition H.^ Si,; Alg Ca K2 Na., Oj^ + 5H,, O, analogous to 

 stilbite, with calcium largely replaced by alkalies. Complete optical determina- 

 tions not made, but appears orthorhombic. Occurs in rhyolite-tufT from Durkee, 

 Oregon. l. mci. l. 



