MICA NACSE. 

 represents magnesia, potash, lithia and the 

 other bases, including alumina. 



See BioTiTE, Lepidolite, Muscovite, 

 Phlogopite, Lepidomelane, &c. 



Brit. Mus., Case 32. 



M. P. G. Principal Floor, Wall-case 42. 

 Horse-shoe Case, No. 1001. Upper Gallery, 

 Table-case A in recess 4, Nos. 122 to 126. 

 Wall-case 6, No. 4. Table-case B in recess 

 6, Nos. 140 to 149. 



Mica Nacre. See Margarite. 



Micaceous Iron. The name given to 

 the vai'ieties of Hematite which possess a 

 micaceous structure. 



M. P. G. ' Principal Floor, Wall -cases 

 48 f British); 18 (Foreign). 



Micaceous Uranitic Ore, Kirwan. See 

 Chalcolite and Uranite. 



MiCARELLE. The name given by Kirwan 

 to Pinite, from its resemblance in external 

 characters to Mica. 



MiCHAELiTE. A white, fibrous, pearly 

 variety of Opal, from the Island of St. 

 Michael, in the Azores S.G. 1'88. 



Analysis, bv v. KoheJl : 



Silica / . . . . 83-65 

 Water 16-35 



100-00 



MiCROCLINE, or MiKROKLINE, Breit- 



haupt. A green and blue variety of Fel- 

 spar (Orthoclase), exhibiting a play of 

 colour, and containing nearly equal quan- 

 tities of soda and potash. S.G." 2-582 to 2-56. 

 Analysis, from Greenland, by Utendoffer : 



Silica 66-9 



Alumina .... 17*8 



Peroxide of iron . . .0-5 



Lime 0-6 



Soda 6*5 



Potash 8-3 



. trace 



100-6 

 Localities. Kangerdluarsuk, in Greenland, 

 with Sodalite and Eudiah'te. Norway, at 

 Laiirvig, Arendal, and Fredericksvarn, in 

 Zircon-syenite, associated with Sodalite and 

 Eukolite. 



Name. From f^izfog, little, and x>^Um, to 

 incline. 



MiCROCOsaiic Salt, Dana. See Ster- 



CORITE. 



MiCROLiTE, Shepard. A mineral proved 

 by A. Hayes to be identical with Pyro- 

 chlore. Colour pale vellow to brown. H. 5-5. 

 S,G. 5-4. 



Analysis, by Hayes ; 

 Colum.bic acid . . . 79'60 



MIKROBROMITE. 239 



Peroxide of iron . . . 0-99 

 Oxides of uranium and man- 

 ganese .... 2-21 

 Lime . '. . . .10-87 



Lead 1-60 



Tin 0-70 



95-97 



The light coloured crystals seem to be 

 nearly pure columbate of lime. 



Locality. The Albite vein, Chesterfield, 

 Massachusetts, U. S., associated with red 

 and green Tourmaline. 



Name. From At/j£?«f , small, and A/fo?, stone. 



Brit. Mus., Case 38. 



MiDDLETONiTE, J. F. W. Jolinson. A 

 Mineral Resin, occurring in layers, or in 

 rounded masses seldom larger than a pea. 

 Colour reddish-brown ; by transmitted light 

 deep red. Lustre resinous. Transparent in 

 thin splinters. Streak light brown. Brittle, 

 but easily cut with a knife. Blackens on 

 exposure to air. No taste nor smell, S.G. 1 '6. 



Comp. C20H10 + HO = carbon 86-57, hy- 

 drogen 7-77, oxygen 5-66 = 100. 



Analysis, hj Johnson : 



Carbon . . . .86-43 



Hydrogen .... 8-01 

 Oxygen .... 5*56 



100-00 

 BB not altered at 400° F. (210° C.) ; on 

 a red cider burns like resin. Softens and 

 melts in boiling nitric acid, with the emis- 

 sion of red fames ; affords a brown floccu- 

 lent precipitate on cooling. 



Localities. Middleton Collieries, near 

 Leeds, between layers of coal, about the 

 middle of the main coal, or Haigh Moor 

 seam. Newcastle. 



MiEMiTE, A variety of Rhomb-spar, 

 from Miemo, in Tuscany. 

 Brit. ]\Ius., Case 47. 



MiEsiTE, Beudant. A broTvai variety of 

 Pyromorphite, from Mies, in Bohemia. 

 Analysis, by Kersten : 



Phosphate of lead , .89-27 



Chloride of lead . . , 9-66 

 Phosphate of lime . . 0*85 

 Fluoride of calcium . .0-22 



100-00 

 MiKROBRoanTE, Breithaupt. Crystalline 

 form cubic. Colour between asparagus- 

 green and greenish -grey, becoming ash- 

 grey and opaque on ex'posure. Translu- 

 cent. Lustre adamantine. Streak Avhite. 

 Very sectile and malleable. Fracture irre- 

 gular. H. 2-5 to 3. S.G. 5-75 to 5-76. 

 Comp. Ag Br + 3Ag CI. 



