4()8 KECOKD OF SCIENCE FOE 1«87 AND 1888. 



yellow; it is trauslucent aud resembles chalcedony. It is optically, 

 imiaxial aud uegative. The hardness is about 5 aud the specific gravity 

 3.053. An analysis yielded the following results: 



I^Os CO, CaO FeO Na20 K.O H2O 

 38.44 6.29 53.00 0.79 0.89 O.il 1.37 = 100.89. 



This leads to the formula 4 Gag PgOs + 2 Ca CO3 + H2O. The locality 

 where it has beeu found, though only very sparingly, is the apatite re- 

 gion in the parish of Bau)le, Norway. Named after by W. C. 



Brogger and Backstroin in the ffifversigt Vet.-Akad. Forhaudlingar, 

 Stocliholm, 1887, }). 493. 



Bihydro-fhenardite. — A sodium sulphate, allied to theuardite, but, as 

 the name suggests, containing two molecules of water. It crystallizes 

 in the mouoclinic system. It forms a thin bed on the shores of Lake 

 Gori, Tiliis, Eussia. (Described by Markovnikoft'iu Jouru. Kuss. Phys. 

 Chem., and an abstract in the Berichte deutsch. Chem. Ges. Berlin, 

 1887, p. 546). 



Edisonite.—A rare mineral consisting of titanium dioxide and (if dis- 

 tinct from rutile) the fourth form in which this oxide is known to occur in 

 nature- The original specimen was found in 1879 by VV. E. Hidden at 

 the Whistnant gold mine, Polk County, North Carolina, in the concen- 

 trations of placer washings. It was associated witb zircon, xenotime, 

 rutile, monazite, and a number of other species. It has a bronze-yellow 

 or golden-brown color, a resinous to adamantine luster and a yellowish 

 white streak. The hardness is about 6 aud the specific gravity 4.26 to 

 4.28. The symmetry of the form is that of an orthorhombic crystal aud 

 the crystallographic study by Des Cloizeaux (Bull. Soc. Min., 1886, 

 vol. IX) shows that it does not vary very widely from the tetragonal type, 

 and in angle bears a certain relation to rutile; he calls it, in fact, a 

 dimorphous form of rutile. A qualitative examination by Damour 

 showed it to be essentially TiOa in composition and a more thorough 

 analysis by Penfield, undertaken later, has confirmed this and proved 

 the absence of all other substances except a trace of iron. Named after 

 Mr. Thomas A. Edison, by W. E. Hidden, in Amer. Jouru. Sci., Oc- 

 tober, 1888, vol. XXXVI, p. 272. 



Eudidymite. — A new silicate of sodium and beryllium from the island 

 Obere Aro in the Langesundfjord, Norway. In his preliminary account 

 Brogger describes it as occurring in tabular mouoclinic crystals having 

 the axial ratio a:h: c=1.7107: 1: 1.1071, fi=SQ^ 14i'. The crystals are 

 twins with the basal planes as twinning plane, which is also the direc- 

 tion of cleavage. The color is white and the luster vitreous or pearly. 

 The hardness is 6 and the specific gravity 2.553. The optic axes lie in 

 the plane of symmetry and the acute positive bisectrix makes an angle 

 of 580 30' with the vertical axis in the acute angle of (5. The first an- 

 alysis by Flink made the mineral contain aluminium instead of beryllium- 

 This was corrected by Nordenskiold, Avhose analysis gave 



SiOa BeO NaaO HjO 



73.11 10.02 12.24 3.79=99.70. 



