HYALOMELAN. 



Localities. — English. Whinstone quar- 

 ries, south of Newcastle. — Irish. Donald's 

 Hill, CO. Down. — Foreign. Scheranitz in 

 Hungary, in am^-gdaloid ; Walsch in Bo- 

 hemia, in clinkstone. 



Name. From i'aAo?, glass, in allusion to 

 its resemblance to that substance, and >-'6o;, 

 stone. 



Brit. Mus,, Case 21. 



M.P.G. Hor:>e-shoe Case, Nos. 764, 765. 



Hyalojielajt, Hausmann. A variety of 

 Tachylite from Vo^lsgebirge. S.G. 2'7144. 



Comp. (R3 +:^*l) si, or 2(K, Xa, Ca, Mg, 



Mn, Fe) fei-|-(Al Fe) is'i. 



Analysis, by C. Gmelin : 



Silica 50-22 



Titanic acid . . . .1*42 

 Alumina .... 17-84 

 Protoxide of iron . . .10-27 



Lime 8-25 



Magnesia .... 3'37 



Soda 5-18 



Potash 3-87 



Protoxide of manganese . 0*40 

 Water and ammonia . . 0'50 



HYDEARGYLLITE. 



183 



101-31 

 Name. From vkXos, glass, and /xi>M^, 



black ; in allusion to the ease with which it 



melts BB to a blackish opaque glass. 



Hyalophane, v. Waltershausen. A variety 



of Orthoclase containing baryta. Occurs in 



dolomite. 



Analysis, by Von Waltershausen : 



Silica 45-65 



Sulphuric acid . . . 4-12 

 Alumina .... 19-14 



Baryta 21-32 



Lime 077 



Magnesia . . . .0-73 



Soda 0-4S 



Potash 8-23 



Water 054 



100-00 

 S.G. (of transparent variety) 2-805 : (of 

 translucent variety) 2-901, 



Name. From vccXo?, glass, and (pochca, to 

 seem. 



Hyalosideeite, Walchner, A variety of 

 Chrysolite, occurring in yellowish- and red- 

 dish-brown crj-stals, imbedded in brown 

 basaltic amygdaloid, at the Kaiserstuhl in 

 the Breisgau. Translucent at the edges, 

 where it exhibits a hyacinth-red colour. 

 Streak brown. H. S'o. S.G. 3-287. 



Comp. (JMg + iFe)5 Si, with an excess 



of Mg Si, a large quantity of the protoxide 

 of iron being replaced by magnesia and 

 other bases. 



Analysis, by Walchner : 



Silica 31-63 



Alumina .... 221 

 Protoxide of manganese . 0-48 

 Magnesia .... 32-40 

 Protoxide of iron • . .28-49 



Potash 2-69 



Chromium .... trace 



97-90 



BB if not naturally magnetic, it becomes 

 so when heated to redness, when it also 

 turns black; at a higher temperature, it 

 fuses to a black magnetic globule. With 

 borax or microcosmic salt, gives the reactions 

 of iron, and with microcosmic salt, immedi- 

 ately a skeleton of silica. 



Dissolves with difficulty in cold, concen- 

 trated muriatic acid, and yields a jelly on 

 evaporation. 



Locality. The Kaiserstuhl in the Breis- 

 gau, in amygdaloid. 



Name. From iituXoi, glass, and a-id-yj^oi, iron. 



Brit. Mus., Case 25. 



Hyblite. a pseudomoi-ph, after Augite. 



by 



Comp. RSi + -8 



Si) 



+ 4H 



. 



Analysis (mean 



of 



many analyses). 



Waltershausen : 









Silica . 







. 40-86 



Alumina 







. 10-22 



Peroxide of iron 





. 20-68 



Lime . 







. 4-53 



Magnesia 







. 2-61 



Soda . 







. 4-05 



Potash 







. 1-12 



Water . 







. 15-93 



100-00 

 Hydeargyllite, G. Ease. The name 

 v/hich has been given to crystallized Gibb- 

 site. Occurs in regular six-sided prisms, 

 or in prisms with twelve faces, resulting 

 from the combination of two hexagonal 

 prisms. Colour reddish- white. Translu- 

 cent or transparent in thin laminae. Lustre 

 vitreous; on cleavage-faces pearly. H. 2-5. 

 S.G. 2-87. 



k4 



