Cs 
Formation of Crystals in Geodes. 
| 1ess 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- 
cessary and idle, will, by being very long and patiently” 
continued, end in — . considerable public utility. 
iter of the article in thee a 
é “NA. Review. 
Boston, May 19th. 
Arr. xx. .—Facts tending to illustrate the formation of 
crystals in geodes. 
great number and diversity of crystals, in the min- 
ngdom, eee prove, that natural modes o = 
have existed, and probably still exist, which ou 
hemistry is unable to imitate, or imitates very ers 
feetly. Who can inform us, in what prige the innumera- 
ble crystals of pres found in almost every geological 
formation, and remarkable, in differdut cases, for their 
transparency, the geometrical accuracy an exquisite 
beauty of their finis h, and occasionally for their great size, 
were dissolved and crystallized ? Was it effected through 
the medium of water, containing fixed alkali or fluoric 
acid, with the subsidiary aid of heat, and if so, or y 
other foreign agents have been employed, why have the 
numerous analys ses of. quartz given us no traces of these 
=e or of any ‘power adequate to produ 
If nothing satisfactory can be said on this subje 
less shall we be prepared to answer a similar inquiry 
respect to the emerald, the chrysoberyl, the sapphi rey the 
ruby, and the Sariond, The topaz, indeed, contains flu- 
oric acid ; and the encreasing number of minerals, in which 
ss manalysis continues to discover this powerful agent 
countenance the sue Poole that it may 
