ON SPURIOUS CRYSTALS. Q3 



d. Level of the pond of Berre. 



C D. Gallery that conveys the water from the pond of 

 Citis into the well. 



D E. The well, in which are the pumps. 



E F. The cast iron c^i Under. 



F G. The wooden trough. 



G H. The canal cut through the rock, 



O. The steam engine. 



g, h. Aqueduct bridges. 



K K K K. Pillars of masou-work, supportij^g the iron cy- 

 linder. 



K m. Height of the first hill. 



iir. 



Remarks on some Pseudomotphoses observed in the Sid)Stances, 

 that form Part of the Mlneralogkal Collection of the Council 

 of Mines: by Mr. Tonnelier, Keeper of the Mineralogical 

 Cabinet to the Council*. 



INERALS that crystallize regularly do not always ap- Stones assui^ 

 pear under those figures, that may be considered as appropri- ^°^s not their 

 ate to them. Frequently they assume those of organized 

 bodies, and sometimes those of substances included like 

 themselves in the mineral kingdom, but of a different nature. 

 These borrowed forms have been designated under the names These called 

 o( pseudomorphoses, or pseudocrystals; and these are the more P^eudomor- 

 suitable, because, if they do not always deceive us, they may pseudocry- 

 at least under certain circumstances impose upon us with re- ^^^^^' 

 spect to their real origin. In some cases too the}^ present us 

 with enigmas not easy to explain, since we cannot always con- 

 ceive what substance it is, the natural figure of which they 

 have borrowed, though we soon detect those that have as- 

 sumed it, under the mask by which they are concealed. 



The pseudomoi-phoses I have chiefly in view in writing these steatite and 



observations are thus far remarkable, that they appear in mi- serpentine ap- 



l^ear in the 



• Jounial dcs Mines, No. llG, p. 155, 



nerals, 



