S-ILICIFEROUS HYDRATE. 

 springs of the Geyser forms reniform, sta- 

 kctitic, fibrous, porous, cauliflower-like, and 

 sometimes even compact incrustations. 



Brit. Mus., Case 21. 



M.P. G. Upper Gallery, Wall -case 1, 

 ]S^3. 95— 99 (Ascension); 127, 128 (New 

 Zealand) ; Table-case A in recess 4, No. 4 

 (Iceland). 



SiLiciFERous Hydrate of Alumixa, 

 Phillips. See Collyrite. 



SiLiciFERous Oxide of Cerium. See 

 Cerite. 



SILICIFEROUS Oxide of Manganese, 

 Phillips. See Rhodonite. 



SiLiciFiED Wood. Wood petrified by 

 silica or quartz, and sometimes converted 

 into Chalcedony or Agate. It usually retains 

 the structure of the original wood, and in 

 the silicified palm-trees found in the Desert 

 near Cairo, the arrangement of the cellular 

 tissue is also preserved. Very fine examples 

 of this conversion of wood into stone are 

 also met wdtli in the Island of Trinidad and 

 other places. 



Brit. Mus., Case 22. 



31. P. G. Horse-shoe Case, Nos. 755, 

 758, 762. Case on model No. 29 (Antigua) ; 

 Lower Gallery (west side), on floor near the 

 stairs. Upper Galler}'-, Wall-case 42, Nos. 

 38 to 44 (British), 45. 



SiLiciTE. The name given by Thomson 

 to a yellowish-white Labradorite, from An- 

 trim in Ireland. It has a vitreous lustre, 

 and breaks with a conchoidal fracture. S.G. 

 2-66. 



Analysis, by Thomson : 



Silica ...... 54-8 



Alumina . . . . 28 4 



Peroxide of iron . . . 4'0 



Lime 12-4 



Water ... . . .06 



100-2 

 SiLLiMANiTE, Bowen. Oblique : primary 

 form an oblique rhombic prism. Cleavage 

 perfect and brilliant. Occurs in slender 

 prisms,often flattened and striated,imbedded 

 in Quartz ; also fibrous, columnar, and com- 

 pact massive. Colour dark grey, passing 

 into clove-brown. Translucent to trans- 

 parent. Lustre vitreous, approaching sub- 

 adamantine on the cleavage face. Streak 

 white. Brittle, and easily reduced to pow- 

 der. Fracture uneven, splintery. H. 6 to 

 7-25. S.G. 3-23 to 3-26. 



Comp. Anhydrous silicate of alumina, or 



Al Si = alumina 63, silica 37 = 100. 



Analysis, from Chester County, by Silli- 

 man : 



SILVER GLANCE. 347 



Silica 37-65 



Alumina .... 62-41 



100-06 



BB alone unaltered : with borax fuses 

 slowly to a transparent colourless glass. 



Localities. Connecticut : at Chester, near < 

 Saybrook, in a vein of gneiss; Falls of the 

 Yantic, near Norwich ; Yorktown, New 

 York. 



Name. After Prof. Silliman. 



Brit. Mus., Case 26. 



Siliimanite may be readily distinguished 

 from Anthophyllite, which it resembles, and 

 for which it M^as formerly mistaken, by its 

 superior hardness. For fibrous massive va- 

 rieties, see BucHOLZiTE and Fibrolite. 



SiLVANE Blanc, Brochant. Sylvanite 

 of Nagyag, in Transylvania. 



SiLVANE Graphique, Brochant. Gra- 

 phic Tellurium. Sylvanite of Off'enbanya. 



SiLVANE Lamhlleux, Brochant. Foli- 

 ated Tellurium. See Nagyagite. 



SiLVANE Natif, Brochant. See Native 

 Tellurium. 



SiLVANiTE, Haidinger, Nicoh See Sylva- 

 nite. 



Silver-black, Jameson. An earthy form 

 of Silver Glance, of a dark bluish -black 

 colour, found in several of the mines of 

 Saxony and Hungary, associated with other 

 ores of silver. 



Silver Glance, Jameson. Cubical ; pri- 

 mary form the cube : also occurs in octahe- 

 drons and %-hombic dodecahedrons, with 

 traces of dodecahedral cleavage. Also reti- 

 culated, dendritic, stalactitic and amorphous. 

 Colour blackish lead -grey; acquiringon 

 exposure a superficial iridescent tarnish. 

 Opaque. Lustre metallic. Malleable and 

 sec tile, yielding easily to the knife, and 

 cutting like lead. Streak shining and like 

 the colour. Flexible. Difficultly frangible. 

 Fracture small-grained-uneven, sometimes 

 inclining to imperfect-conchoidal. H. 2 to 

 2-5. S.G. 7-2 to 7-36. 



Fig. 386. Tig. 387, • Fig. 388. 



Comp. Sulphide of silver, or Ag S== silver 

 87-1, sulphur 12-9 = 100. 



Analysis, from Joachimsthal, by Lindaker: 



Silver 77-58 



Sulphur .... 14-46 

 Iron ..... 2-02 



