Colorado, over the elevated plateau of the Sierra Madra, it is
equally salubrious and temperate. The rainy season falls in the
summer months, and but seldom is snow seen even upon the mountain
tops. Towards the Colorado river it is much drier and more
torrid, but by no means unhealthy; nor does it prevent out door
work the whole of the day during the heated term of summer.

"The great riches of the country, however, are a total waste at
the present time, but which the Pacific railroad will at once
develop, and make to itself the foundation of a vast revenue. Irefer to its metallic wealth, the silver, gold, and copper mines
that abound in almost every mountain and valley, between the Rio
Grande and the Gulf of California.

"The ores of Chihuahua and Sonora [now Arizona. S. M.] are
chiefly sulphuret (lead or iron), or native silver in porphyritic
or stratified limestone rocks passing at greater depths into
igneous rocks. From loose piles lying upon the surface and
evidently picked over, I procured specimens of silvier and
copper. Three samples representing points on the line of our
exploration about equi-distant from each other, viz.: the Rio
Grande, the neighborhood of Tubac, and within 90 miles of the
junction of the Gila and Colorado rivers, were submitted to Dr.
I. K. Chilton, of New York, for analysis. He found in one sample
of lead ore (argentiferous galena), by fire assay 71 per cent. of
lead, and the "LEAD YIELDED SILVER EQUIVALENT to 128 ounces, 1
dwt. to the ton" (of 2000 pounds).

"In another, he found the lead obtained from it to yield silver
in the proportion of 72 ounces 5 dwts. to the ton or 2000 pounds.