156 GLAUCOSIDERIT. 



Analysis, by Schnedermann : 



Silica 56-49 



Alumina . . . .12-23 

 Protoxide of iron . . . 10-91 

 Protoxide of manganese . 0"50 

 Magnesia .... 7-97 



Lime 2-25 



Soda, with traces of<potash . 9*28 



99-63 

 Locality. — The island of Syra, one of the 



Cyclades, in mica-slate. 



Name. From ■yXa.vx.o?, bluish-green, and 



(pcc'ivca^ to appear, 



GLAUCOSIDERIT. See ViVIANITE. 



The name is derived from y'kavx.k, bluish- 

 green, and a-i^'/i^o;, iron. 



Glimmer, Kirwan, Jameson, Werner. See 

 Mica. The name is confined by Haidinger 

 and Hausmann to the variety called Mus- 

 covite. 



Glinkite, Fomanowski. A greenish va- 

 riety of Chrysolite, found in talcose slate at 

 Perm, in Russia ; and at Tunaberg, in gneiss, 

 with Augite and Garnet. 

 Analysis, by v. Beck : 



Silica 39-21 



Magnesia .... 44-06 

 Protoxide of iron . . . 15*45 



100-72 

 Globular Quartz. A variety of com- 

 mon Quartz, found of a black colour, in 

 chalk, at Dover ; and at Knockmahon Cop- 

 per Mines, near Bunmahon, S. Waterford. 



Glottalite, Thomson. A variety of 

 Analcime, occurring in small aggregated 

 and irregular, white or colourless crystals, 

 somewhat like Jig. 212 ; in greenstone at 

 Port Glasgow in Scotland. Lustre vitreous. 

 H. 3to4. S. G. 2-18. 



Fig. 212. 



Comp. 3Ca3 Si2 + 3AI Si2 + 24H. 

 Analysis : 



Silica . . . . ' . 37*01 



Alumina 



. 16-31 



Peroxide of iron . 



. 0-50 



Lime . 



. 23-93 



Water . 



. 21-25 



9900 

 Name. From Glotta, the river Clyde, and 

 do;, stone. 

 Gmelinite, Brooke. Or Soda-Chabasite, 



GOETHITE. 



with which it isheteromorphous. Hexagonal : 

 primary form an obtuse rhombohedron. Oc- 

 curs in flat six-sided prisms, terminated at 

 both extremities by truncated six-sided 

 pyramids. Fig. 212*. Colour white or yel- 

 lowish-white passing into flesh-red. Lustre 

 vitreous. Translucent. Surface of the 

 prisms striated horizontally. Streak white. 

 Bi-ittle. Fracture uneven. H. 45. S.G. 

 2-04 to 2-12. 



Fig. 212*. Fig. 213. 



Comp. Like that of Chabasite, but dis- 

 tinguished from it by having a portion of 

 the lime replaced by a corresponding quan- 

 tity of soda: (Na2, Ca)3 si2 + 3AL Si^ + 



18H = si]ica 47-57, alumina 19-85, lime 3*67, 



soda 8-05, water 20-86. 



Analysis, from Glenarm, by Connel : 



Silica 48-56 



Alumina . . . .18-05 

 Peroxide of iron . . .0-11 

 Lime ..... 5-13 



Soda 3-85 



Potash 0-39 



Water 21*66 



98-75 



When held in the flame of a candle flies 

 off in minute scales. In the matrass yields 

 water and falls to powder. 



BB shrinks up and fuses to a blistered, 

 slightly translucent enamel. 



Forms a jelh^ of silica Avith muriatic 

 acid. 



Localities. Coating cavities in amygda- 

 loidal rocks in the trap districts of the N. 

 E. of Ireland, and at Talisker in Skye. Also 

 in a similar manner at Montecchio Mag- 

 giore, and at Castel in the Vicentine. 



Name. The name Gmelinite was proposed 

 by Sir David Brewster in compliment to 

 G. C. Gmelin, professor of chemistry in the 

 University of Giessen. 



Brit. Mus., Case 27. 



Goethite, Phillips. Gothite, Beudant, 

 Dana, Greg ^ Lettsom. Khombic: primary 

 form a right rhombic prism : occurs iu 

 prisms longitudinally striated, and often 

 flattened parallel to the shorter diagonal : 

 also fibrous, reniform, and in minute laminaa 

 or tables modified at their edges by oblique 

 facets. Colour reddish and blackisli- brown, 

 yellowish by reflected light, and ofteu 



