136 FASERZEOLITH. 



Faroe in stalactites, sometimes 3 inches 

 long. 



Name. From the locality where the finest 

 specimens are found : Faroe, and Ai^t?, stone. 



Faserzeolith, Werner. See Natro- 



LITE. 



Fassaite. a variety of Pyroxene of a 

 beautiful grass- green colour, with a high 

 lustre. It is found in the Valley of Fassa, 

 in the Tyrol, whence the name Fassaite. 



Brit. Mus.. Case 34. 



M. P. G. Horse-shoe Case, No. 1042. 



Fat Quartz, Kirwan. See Greasy 

 Quartz. 



Faujasite, Damour ; Faujassite, Du- 

 frenoy. Dimetric. Occurs in octahedrons. 

 Colourless to brown;, with a vitreous and 

 uneven fracture. H. 5, S.G. 1-923. 



Fig. 187. 



Comp. K Si + Al Si2 + 9 H = silica 46, alu- 

 mina 17, lime 5, soda 5, water 27 = 100. 



Analysis, by Damour : 



Silica ..... 46-12 

 Alumina .... 16-81 

 Lime ..... 4-90 

 Soda ..... 5-09 

 Water ..... 27-02 



99-83 



BB intumesces and fuses to a white blebby 

 enamel. 



Soluble in muriatic acid. 



Locality. Kaiserstuhl, in Baden, with 

 black Augite. 



Name, by Damour, in honour of Faujas de 

 Saint- Fond, a celebrated naturalist. 



Brit. Mus., Case 29. 



Fayalite, is a pure Iron-Chrysolite, or 

 an anhydrous silicide of iron, in which a 

 large quantity of the protoxide of iron is 

 replaced by magnesia and other bases. It 

 is sometimes fused and blistered, sometimes 

 Avith a crystalline structure. Colour greenish 

 or brownish-black. Sometimes iridescent. 

 Opaque. Lustre semi-metallic in places. 

 Strongly attracted by the magnet. H. 6-5. 

 S.G. 4-138. 



Comp. (Of the soluble portion) Fe^ Si = 

 protoxide of iron 70-45, silica 29-55—100-00. 

 Analysis, by Fellenberg : 



Silica ..... 31-04 

 Protoxide of iron . . . 62-57 

 Lime . , . . . 0-43 



FELDSPATH BLEU. 



Protoxide of manganese . 0*79 

 Oxide of copper . . . 0°32 

 Oxide of lead . . . 1'71 

 Alumina .... 3*27 

 Sulphur and chlorine . . traces 



100-13 



BB fuses ver}' easily and quietly, with 

 evolution of sulphurous acid, to a black me- 

 tallic globule, which is magnetic. 



Strong-fuming nitric acid converts it into 

 a jelly. 



Localities. — Lrish. In small detached 

 masses at Slievecarrach, one of the Mourne 

 mountains. Tullybrick, Ballinascreen. The 

 foot of Slieve Gallion, in Londonderry. It 

 is also met Avith in volcanic rocks at Fayal, 

 whence the name Fayalite. 



Brit. Mus., Case 26. 



Feather-aeum, or Federalaun. See 

 Alunogen and Halotrichtte. 



Feather-ore, or Federerz. See He- 

 teromorphite. 



Feather Zeolite. See Natrolite. 



Felospath, Haiiy ; Feldspar; Feld- 

 steix, Hausmann; Felspar, Phillips. 

 Under this head are comprised several mi- 

 nerals, varying much in appearance, and 

 presenting numerous and complicated crys- 

 talline forms. It has been divided into several 

 species and varieties, the principal of which 

 are described under the following names : — 

 Adularia, Albite, Amazon-stone, Andalusite, 

 Andesine, Anorthite, Cancrinite, Erythrite, 

 Hatiyne, Labradorite, Lapis-lazuli, Leucite, 

 Moonstone, Murchisonite, Nosean, Oligo- 

 clase, Orthoclase,^ Petalite, Ryacolite, Soda- 

 lite, and Variolite. The word Felspar is 

 derived from the German name Feldspath, 

 or field-spar, in allusion probably to the 

 crystals being found loose on the surface of 

 some parts of the country.* Several varieties 

 of Felspar are used in jewelry; but all of 

 them are indebted for this distinction, not 

 on account of their possessing any trans- 

 parency, but for their mutable reflection of 

 light, or to their being chatoyant. 



Brit. Mus., Case 29. 



M. P. G. Horse-shoe Case, Nos. 944, 955 

 to 959, 965, 972, 973, 1039. Upper Gallery, 

 Wall-case 6, Nos. 3 & 3a. 



Feldspath Apyre, Haiiy. See Anda- 

 lusite. 



Feldspath Argilliforme, Haiiy. See 

 Kaolin. 



Feldspath Bleu, Haiiy. See Lazu- 

 lite. 



* Kirwan states that tlie word Felspar is de- 

 rived from/^/5 (a rock), from the common occur- 

 rence of the mineral in granite. 



