282 Formation of Crystals in Geodes. 
business of genius to conquer difficulties which, to ordinary 
men like us, appear insurmountable ; and it may even hap- 
pen that some of these very efforts, which on the authori- 
ty of Mr. Quinby’s opinion are to be considered as unne- 
cessary and idle, will, by being very long and patiently 
continued, end in inventions of considerable public utility. 
The writer of the article in the — 
N. A. Review. , 
Boston, May 19th. " 
Ant. XX.—Facts tending to illustrate the formation A 
, crystals in geodes. 
Tue great number and diversity of crystals, in the min- 
eral kingdom, sufficiently prove, that natural modes of so- 
lution have existed, and probably stil! exist, which our 
chemistry is unable to imitate, or imitates very imper- 
fectly. Who can inform us, in what mode the innumera- 
ble crystals of quartz, found in almost every geological 
formation, and remarkable, in different cases, for their 
transparency, the geometrical accuracy and exquisite 
beauty of their finish, and occasionally for their great size, 
were dissolved and crystallized ' ? Was it effected through 
the medinm of water, containing fixed alkali or fluoric 
acid, with the subsidiary aid of heat, and if so, or if any 
other foreign agents have been employed, why have the 
gumerous analyses of quartz given us no traces of these 
agents, or of any other power adequate to produce the ef- 
fect. 
Tfnothing satisfactory can be said on this subject, still 
less shall we be prepared to answer a similar inquiry with 
respect to the emerald, the chrysoberyl, the sapphire, the 
ruby, and the Poke The topaz, indeed, contains flu- 
oric acid ; and the encreasing number of minerals, in which 
modern analysis continues to discover this powerful agent, 
seems to countenance the supposition, that it may have 
been an active agent, in effecting the solutions of earthy 
substances ; although it is not easy to understand how fluo- 
ric acid would have been very efficient, in dissolving a 
mineral substance, in which itself forms an essential con-. 
stituent part. 
