184                             EXPEDITION  TO  THE
the impression that it is in place, as we are informed that it " is found in detached pieces and solid masses, in veins and beds in red clay, and accompanied by sulphurate (sulphate?) of barytes, calcareous spar, blende, iron pyrites, and quartz."* Now, that all the indications mentioned by those who have seen these mines, justify a belief that the lead is not in its original site, we consider as satisfactorily proved. That the lead ore as well as the accompanying minerals, must be out of place, is equally apparent, from the circumstance, that while the clay is said to repose upon the limestone, the ore is not stated to have ever been worked in this rock. We are told, that " the greatest proportion of lead ore is, however, found imbedded in, and accompanied by, the sulphate of barytes resting in a thick stratum of marly clay, bottomed on limestone rock. The rock is invariably struck at a depth of from fifteen to twenty feet, and puts a stop to the progress of the miner in a common way. To go further, it is necessary to drill or blast, and this creates an expense which the generality of diggers are unwilling to incur, if not unable to sup-port."t Again, we find " in digging down from fifteen to twenty feet, the rock is generally struck; and as the signs of ore generally give out on coming to the rock, many of the pits are carried no further."! Finally, in his visit to Dubuque's lead mines, performed in the year 1820, Mr. Schoolcraft observed, that the ore " had been chiefly explored in alluvial soil;" though he at the same time states, that " it generally occurs in beds or veins."§ From the specimens which we have seen, as well as from
* View of the Lead Mines of Missouri. New York, 1819. p. 67.
t Ibid, p. 69.                       * Ibid, p. 108.
^ Schoolcraft's Narrative Journal of Travels, &c. p. 344.