172 NAKRATIVE OF THE EXPEDITION. 



the river bluffs, we pursued a path over undulating hills, exhibit- 

 ing a half prairie, and quite picturesque rural aspect. On reach- 

 ing the diggings, the most striking part of them, but not all of 

 them, exhibited excavations such as the Indians only do not seem 

 persevering enough in labor to have made. 



The district of country called Dubuque's Mines, embraces an 

 area of about twenty-one square leagues, commencing at the 

 mouth of the Little Maquaquity River, sixty miles below Prairie 

 du Chien, and extending along the west bank of the Mississippi 

 Eiver, seven leagues in front by three in depth. The principal 

 mines are situated on a tract of one square league, beginning im- 

 mediately at the Fox village of Aquoqua, or the Kettle chief, 

 and extending westwardly. This is the seat of the mining opera- 

 tions carried on by Dubuque, as well as of what are called the 

 Indian Diggings, 



Geologically it is the same formation that characterizes the 

 mines of Missouri; but there are some peculiarities. The ore 

 found is the common sulphuret of lead, with a broad foliated, 

 or lamellated structure, and high metallic lustre. It occurs 

 massive and disseminated, in a red loam, resting on a hori- 

 zontal limestone rock. Sometimes small veins of the ore are 

 seen in the rock, but it has been generally explored in the soil. 

 It generally occurs in narrow beds, which have a fixed direction; 

 these beds extend three or four hundred feet, when they cease, 

 or are traced into crevices in the rock. At this stage, the pur- 

 suit of ore, at most of the diggings, has been abandoned, fre- 

 quently with small veins of the metal in view. No matrix, so 

 far as I observed, is found with the ore which is dug out of the 

 goil, unless we may consider such an ochery oxide of iron, with 

 which it is slightly incrusted. Occasionally, pieces of calcareous 

 spar are thrown out with the earth in digging after ore. I picked 

 up from one of these heaps of earth a specimen of transparent crys- 

 tallized sulphate of barytes ; but this mineral appears to be rare. 

 There appears to be none of the radiated quartz, or white opaque 

 heavy spar, which are so abundantly found at the Missouri 

 mines.* 



The ore at these mines is now exclusively dug by the Indian 



* Vide my View of the Lead Mines of Missouri, &.C., New York, 1819. 



