ArPENDix. 565 



from east and ivest leack, is raised from clay diggings, altbougli 

 these diggings may be pursued under the first stratum of rock. 

 Ore from iiorth a^id south leads, is termed " sheet minerals," and is 

 usually taken from rock diggings. The vein or sheet stands per- 

 pendicularly in the fissure, and is usually struck in sinking from 

 six to ten feet. The sheet varies in thickness from six or eight 

 inches, in the broadest part, to not more than one. The great 

 mass found at " Irish diggings" was of this kind. 



I observed, among the piles of ore at Gratiot's, the combination 

 of zinc with lead ore, which is denominated dry hone. It is cast 

 by as unproductive. Mr. B. Gratiot also showed me pieces of 

 the common ore which had undergone desulphuration in the log 

 furnace. Its natural splendor is increased by this process, so as 

 to have the appearance of highly burnished steel. He also pre- 

 sented me some uniform masses of lead, recrystallized from a 

 metallic state, under the hearth of the ash furnace. The tendency 

 to rectangular structure in these delicate and fragile masses is 

 very remarkable. Crystallization appears to have taken place 

 under circumstances which opposed the production of a complete 

 and perfect cube or parallelogram, although there are innume- 

 rable rectangles of each geometric form. 



In the drive from Gratiot's to Willow Springs, we saw a suc- 

 cession of the same objects that had formed the prominent features 

 of the landscape from Galena. The platte mounds, which had 

 , appeared on our left all the morning, continued visible until we 

 entered the grove that embraces the site of the springs. Little 

 mounds of red earth frequently appeared above the grass, to tes- 

 tify to the labors of miners along this part of the route. In taking 

 a hasty survey of some of the numerous excavations of Irish dig- 

 gings, I observed among the rubbish small flat masses of a yel- 

 lowish white amorphous mineral substance of great weight. I 

 have not had time to submit it to any tests. It appears too heavy 

 and compact for the earthy yellow oxide of lead. I should not 

 be disappointed to find it an oxide of zinc. No rock stratum pro- 

 trudes from the ground in this part of the country. The consoli- 

 dated masses, thrown up from the diggings, appear to be silicated 

 limestone, often friable, and not crystalline. Galena is found in 

 open fissures in this rock. 



We reached the springs in the dusk of the evening, and found 



