MONTMORILLONITE. 



Comp. (Ca3 + Mg5) Si2. 

 Locality. Vesuvius, imbedded in crystal- 

 line carbonate of lime with black Mica and 

 minute crystals of Pyroxene. 



Name. *^ After Monticelli, the Neapolitan 

 mineralogist. 



Brit. Mus., Case 25. 



MoNTMOPaLLONiTE, Solvetat A hydrous 

 silicate of alumina, &c., of a rose-red colour. 

 Fragile. 



Analysis, by Damour : 



Silica 50-04 



Alumina .... 20-16 

 Peroxide of iron . . .0-68 



Lime ^-46 



Magnesia . . . .0-23 

 Potash. .... 1-27 

 Water ..... 26-00 



99-84 



Localities. Confolens in Charente. Near 

 St. Jean de Colle, in Dordogne. Montmo- 

 rillon, Dept. of La Vienne. 



Moonstone. A transparent or translu- 

 cent variety of Adularia. It contains blu- 

 ish'-white spots which, when held to the 

 light, present a pearly or silvery play cf 

 coJour not unlike that of the moon. It is 

 held in considerable estimation as an orna- 

 mental stone, but is more prized on the 

 continent than in England. When set in 

 rings and brooches surrounded by small 

 rubies and emeralds, it forms an agreeable 

 contrast to the latter. Fine stones are 

 scarce; the most valued are those, which 

 when cut in a very low oval, present the 

 silvery spot in the" centre. This (and the 

 other varieties of Felspar) is so soft com- 

 pared with other gems and precious stones, 

 that few lapidaries know how to work it to 

 the greatest advantage. (Mawe.) The finest 

 stones are brought from Ceylon. 



Brit. Mus., Case 29. 



3L P. G. Horse-shoe Case, Nos. 955 to 

 957. 



MooNTOSs. A provincial name for Pea- 

 cock coal. 



MoRAss-OKE, Jameson. Morassy Iron- 

 ore, Kirwan. MoRASTERZ, Werner. See 

 Bog-iron-ore. 



Morion. The name given by lapidaries to 

 Eock Crystal of a brownish-black or char- 

 coal-black tint. 



Brit. Mus., Case 20. 



M. P. G. Horse-shoe Case, No. 480. 



MoROXiTE. An opaque, greenish-blue 

 variety of Apatite from Arendal in Norway, 



MOSS AGATE. 245 



and Pargas in Finland. The name is de- 

 rived from ,£^o'?o|«?, an Egyptian stone used 

 in the bleaching of linen. 



Brit. Mus., Case 53. 



INIoRVENiTE, Thomson. A variety of 

 Harmotome occurring in small transparent 

 crystals in mineral veins in granite, near its 

 junction with gneiss, at Strontian in Ar- 

 gyleshire. 



Fig. 295. 



Analysis, by Damour : 



Silica = . . . . 47-60 

 Alumina .... 16-39 

 Peroxide of iron . . .0-65 

 Baryta .... 20-86 



Soda 0-74 



Potash .... 0-81 

 Water 14-16 



101-21 



Brit. Mus., Case 29. 



MosANDRiTE, Erdmann. In large flat 

 prisms, with the lateral edges replaced by 

 planes ; also massive and fibrous. Colour 

 dull greenish- or reddish-brown. Lustre 

 resinous ; of cleavage-face between vitreous 

 and greasy. Translucent in thin splinters . 

 deep-red by transmitted light. Streak grey- 

 ish-brown." H. 4. S.G. 2-93 to 2-98. 



Comp. K3 Si + 2ii5 Si + 4iH. 

 Analysis, b}' Berlin ; 



Silica 29-93 



Titanic acid . . . 9-90 



Peroxide of cerium, Peroxide 

 of lanthanum. Peroxide of 

 didymium . . . 26*56 

 Peroxide of iron, with some 



Peroxide of manganese . 183 

 Magnesia .... 0v5 



Lime 19-07 



Potash 0-52 



Soda 2-87 



Water 8-90 



100-33 



Locality. Brevig in Norway, with Albite 

 and violet Fluor. 



Name. After the Swedish chemist, Mo- 

 sander. 



Brit. Mus., Case 37. 



Moss Agate. A variety of Chalcedony 

 inclosing dendritic or moss-like markings 

 of various shades, and occasionally traversed 

 by irregular veins of red Jasper. 

 K 3 



