84 MOJAVE VALLEY TO MOUTH OF BLACK CANON—MINERALS. 
Captain Robinson and myself should have made the reconnaissance of the cafion; and I 
willingly acceded to his proposition. Before leaving he again warned me against the Pai-utes. 
Their tracks have been discovered in the immediate neighborhood, and one of them was seen 
an evening or two ago watching us from a thicket on the opposite side of the river. It would be 
no easy matter to surprise us in camp; but there is a prospect that the doctor and Mr. Egloff- 
stein, who spend much of their time in geological and topographical excursions, may be carried 
off some day by a straggling party. 
The mountains west of the river are rich in mineral curiosities, Along the bottoms of the 
ravines are found crystals of quartz, in curiously grouped clusters, and great numbers of opals. 
Some of the latter are of considerable size, and promise to prove, when polished, valuable gems. 
