216 LEUCO-GARNET. 



Localities. The finest and most beautiful 

 crystals are found in the older lavas of 

 Vesuvius and Rocca Monfina, and in those 

 of Borghetto, Albano, and Frascati in the 

 neighbourhood of Rome, parts of which are 

 almost entirely composed of it. The Leu- 

 citic lavas of these districts have been used 

 for millstones for the last 2000 years. 

 Between Lake Laach and Andernach on 

 the Rhine, in trachyte. 



From the circumstance of its occurrence 

 in trapezohedrons similar to those of com- 

 mon Garnet, and from its white tint, 

 Leucite was called "White Garnet" by 

 Bergman, and ■' White Garnet of Vesuvius" 

 by Kirwan. It is also known by the name of 

 " White Garnet of Frascati " to the Italians. 



Leucite is easily distinguished from Anal- 

 cime by its infusibility, and by never show- 

 ing faces of the cube. 



It is found altered by decomposition to 

 Kaolin or China-clay. 



Name. From >^ivxc?^ white; in allusion to 

 its colour. 



Brit. Mus., Case 31. 



M. P. G. Table-case A in recess 4, Nos. 

 79 to 83. Table-case B in recess 6, No. 83, 

 &c. Horse-shoe Case, Nos. 1011, 1012, 



Leuco-Garnet. a white rariety of Gar- 

 net found at Tellemarken in Norway, and 

 in Siberia. 



Leucocyclite, Dufrenoy. (From XivyJi?, 

 zvhite, xuzXos, a circle, and x/flo?, stone.^ See 



ICHTHYOPHTHAEMITE. 



Leuoolitk, Dufrenoy. (From XivyJ^^ white, 

 and A/9<jf, stone ) See Leucite. 



Leucolite d'Altenbeeg. See Pycnite. 



Leucolite de Mauleon, La Metherie. 

 See DiPY'RE. 



Leucophake, ^sraarA. Rhombic. Rarely 

 in crystals, usually massive and columnar. 

 Cleavage in three directions. Colour wine- 

 yellow to pale olive-green ; in thin splinters 

 transparent and nearly colourless. Lustre 

 vitreous. Streak white. Strongly phos- 

 phorescent. Becomes electric when heated. 

 H. 3-5 to 4. S.G. 2-964. 



Fig. 259. 



Comp. Silicate, of Glucina and Lime, 



with Fluoride of Sodium, or Ca^ Si^ + Be Si 

 + Na F = silica 45-3, lime 28-0, glucina 127, 

 sodium 7-7, tluorine 6-3 = 100. 

 Analysis, by Erdmann ; 



Silica ..... 47-82 

 Glucina , , , .11-51 



LEVYNE. 

 Protoxide of manganese . 1-01 



Lime 25-00 



Sodimn .... 7*59 



Potassium . . . . 0-26 

 Fluorine .... 6-17 



99-36 



BB fuses to a transparent, violet-coloured 

 globule, which becomes opaque by iiaming. 



Locality. A rocky islet near the mouth 

 of the Langesundfiord in Norway, in syenite 

 with Albite, &c. 



Name. From y^tuxo;, white, and (p^im, to 

 seem. 



Leucopyrite, Shepard. Arsenical. 

 Pyrites in part. Rhombic : primary form 

 a right rhombic prism. Cleavage perfect 

 at right angles to the axis. Generally 

 occurs in masses of a colour between silver- 

 white and steel-grey, with a yellowish tar- 

 nish. Lustre metallic. Streak greyish-black. 

 Brittle. Fracture uneven. H. 5 to 5-5. S.G. 

 7 to 7-4. 



Comp. Arsenide of iron, Fe As^ — arseni(3 

 72-8, iron 27-2, or (Fe, Ni, Co) As^. Some- 

 times Fe2 As3. 



Analysis, from Reichenstein, by Karsten. 

 S.G. 7-09. 



Arsenic .... 65-88 

 Sulphur . . . .1-77 

 Iron ..... 32-35 



100-00 



BB on charcoal fuses to a black magnetic 

 mass, with the evolution of a strong odour 

 of arsenic. 



Soluble in nitric acid with separation of 

 arsenious acid. 



Localities. Cornwall and Devonshire. 

 Schladming in St^n-ia, with Copper Nickel. 

 Reichenstein in Silesia with Serpentine. 

 Loling near Hiittenberg in Carinthia, in 

 Sparry Iron. Freiberg, and Ehrenfrieders- 

 dorf in Saxony. 



Name. From Xivzi; white, and Pyrites. 



This ore is emploj^ed for the production 

 of white arsenic, and also of artificial Orpi- 

 ment. 



Leutrite, Sartorius. An indurated 

 sandy marl, appearing to the naked ey% like 

 a lump of sugar. Colour greyish or yellow- 

 ish. Becomes phosphorescent by friction, 

 even with paper. 



Locality. The Leutra, near Jena. 



Leuzite, Jameson. See Leucite. 



Levyne, Brewster. Hexagonal. Pri- 

 mary form a rhombohedron. Occurs in 

 twin crystals. Crystals often striated. Colour 



