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.XXVIII. Notes on Mineralogy. By the Rev. Samuel Haughton, 



M.D.j Fellow of Trinity College, Dublin*. 



[Continued from vol. xxiii. p. 52.] 



No. XII. Analysis of Sombrerite.. 



THIS rock-mineral is found at Sombrero and other isles of 

 the Antilles, and is imported into Liverpool as a mineral 

 manure. It is formed from the atmospheric decomposition of 

 Guano, and contains numerous casts of land shells. 



Sombrerite. 



Per cent.. 



Silica 0-08 



Phosphate of lime and alumina . 89*64 

 Carbonate of lime ..... 5'00 

 Chloride of potassium .... 2' 81 

 Fluoride of calcium .... 0*10 



Water . .. 0-60 



98-23 

 Loss ... ..... 1-77 



100 00 



No. XIII. Analysis of Pitchy Iron Ore from Kilbride, Glenoid 



splinkeen, co. Wicklow. 

 This ore is associated with Limonite and Psilomelane, and! 

 occurs in considerable quantity. It forms one of the large group 

 of hydrated peroxides of iron, with a larger amount of water than 

 is commonly found. 



It contains no sulphur, no protoxide of iron, and no organic 

 matter. 



Pitchy Iron Ore, Kilbride. 



Per cent. 

 Peroxide of iron . . . 77*15 



Water 20-43 



Silica 0-30 



Alumina trace 



Phosphoric acid . . . 1*60 



99-48 

 The result of this analysis is 



Ee 2 3 + 2iHO. 

 That of Gothite is 



Fe 2 3 + HO; 

 and of Limonite 



Fe 2 3 + 11H0. 



* Communicated by the Author. 



