Dr J. Reinhard Blum on Pseudomorphous Minerals. 243 



Pseudoirwrph. 



Litbomarge, 



Felspar, 



Meerschaum, 



Pyrolusite, 



Hausmannite, 



Manganite, 



Psilomelane, 



Calamine, 



Electric Calamine, 



Tin Ore, 



White Lead Ore, 

 Peroxide of Iron, 

 Brown Iron Ore, 



PjTites, 



White Iron Pyrites, 

 Spathic Iron, 

 Malachite, 

 Chrysocolla, 



Form Imitated. 

 Spar, Fluor-Spar, Calc-Spar, Dolo- 

 mite, Pyromorphite : as C'arnelian, 

 Calc-Spar, Mica, Spathic Iron ; as 

 Semiopal, Calc-Spar. 



Fluor-Spar. 



Calc-Spar. 



Calc-Spar. 



Calc-Spar. 



Calc-Spar. 



Calc-Spar. 



Heavy-Spar, Fluor-Spar, Cube Ore. 



Fluor-Spar, Calc-Spar. 



Fluor-Spar, Calc-Spar, Dolomite, Galena, 

 Pyromorphite, 



Felspar. 



Heavy- Spar, Fluor-Spar. 



Fluor-Spar, Calc-Spar. 



Heavy-Spar, Fluor-Spar, Calc-Spar, 

 Dolomite, Quartz, Comptonite, Blende, 

 Galena, P)Tomorphite, White-Lead 

 Ore, Red Copper Ore. 



Heavy-Spar, Calc-Spar, Quartz, Brittle 

 Silver Ore, Red Silver Ore. 



Brittle Silver Ore. 



Calc-Spar, Dolomite. 



Calc-Spar, White-Lead Ore. 



White-Lead Ore. 



To this catalogue we may add the following : — 



Green Earth, under the form of Haydenite. 

 Chlorophyllite and Fahlunite, under the form of lolite. 

 Rensselserite, under the form of Augite. 



Pseudomorphous changes in the simple salts, produced by 

 a, replacement of the acid or base, admit of easy explanation 

 upon the most common principles of chemistry. Such is the 

 change of carbonate of lime to sulphate of lime (gypsum) by 

 the expulsion of the weaker acid (carbonic) by sulphuric acid, 

 and we need only look to some decomposing pyrites (sulphu- 

 ret of iron) for a source of this acid. Other changes are 

 more difficult of explanation. We shall now notice some of 

 the more interesting facts in Dr Blum's work. 



Gypsum with the form of Anhydrite. — Large deposits of 

 anhydrite have undergone this change to gypsum. In the 

 Canaria Thai, a bed of this mineral in mica-slate consists of 

 gypsum wherever it is exposed. At Bex, in Switzerland, 

 the same fact is observed ; the unaltered anhydrite is inva- 



