Ie 
MINERALS—SALTS AND INCRUSTATIONS. 309 
This Canadian magnesite is not so pure as that of California, and it grows yellow by exposure 
to the weather. 
Another specimen in my collection is entirely different in its character, being crystalline and 
granular, but occurs in masses like limestone. It was presented to me by Dr. Trask, and is from 
the mining region. It is covered with beautifully green crusts or films, which somewhat resemble 
thin scales of silicate or carbonate of copper. This rock was supposed to consist of quartz and lime- 
stone, but had not been examined, when Mr. Hunt, who saw the specimen, immediately recog- 
nized it as nearly identical with the magnesite of Canada, and, on examination, finds that the 
green films consist of oxides of nickel and chromium. There is an almost unlimited supply of 
this mineral at the locality near the Four Creeks. It can be used with great advantage in 
many processes in the arts, and is valuable for the preparation of the various salts of magnesia. 
SALT. 
The principal locality of common salt, near the line of the survey, is in the hills bordering 
the Great Basin, on the eastern side of the elevated plain or Valley of Taheechaypah, and near 
the Tejon Pass. It is said to occur in a thick bed, from which it is excavated by the Indians, 
several mule loads having been taken to the Tejon for the use of the settlement commenced 
by Lieutenant Beale. This salt is said to be granular, very clean, and of excellent quality. 
Not having seen the locality, it is impossible to describe the association of the salt, or to state 
whether it actually occurs interstratified with clay and sand, in the side of a hill, as is repre- 
sented. It is possible that it was formed at the bottom of a small lake which has dried up, or 
which may become dry during the summer. 
A thick crust of salt is formed in this manner by t the annual evaporation of the water of a 
shallow pond, called Casteca Lake, near the summit of the Cañada de las Uvas. In the dry 
season the water all evaporates, and leaves a thick crust of white salt, which the wind acts on 
and blows about like snow. 
A salt lake, or dry lake-bed of salt, is also reported to exist in the lowest part of the northern 
portion of the Colorado Desert. While we were traversing this Desert, an Indian accompanied 
us for a short distance from the Cohuilla villages, and then struck off towards the north for 
salt. Salty incrustations were found around most of the springs of the Desert, and along the 
streams running into it. The incrustation of Salt Creek, crossed November 20, consists of chlo- 
ride of sodium and sul phate of magnesia ; and the crust found on the soil at the Cohuilla vil- 
lages, November 18, is chiefly composed of salt, with sulphate of soda and sulphate of magnesia. 
The Dry Lake, at the extreme end of the Mojave River, in the Great Basin, has a thick incrus- 
tation, formed partly of salt and partly of carbonate of soda and sulphate of magnesia. | 
Salt also occurs in the soil along the Mojave, near the foot of the slope from the Cajon Pass, 
and is associated with carbonate of soda, sulphate of soda, and sulphate of magnesia. A mass 
of rock, at some distance from the river, which appeared moist, was broken into by Lieutenant 
Williamson, and a hard nucleus reached, which was afterwards found to attract moisture, and 
could not be kept dry when wrapped in paper. On examination it proves to contain chloride of 
calcium, in addition to chloride of sodium, nitrate of soda, and sulphate of magnesia. 
The coast and climate of California are particularly favorable to the manufacture of salt from 
sea water. At Monterey, Santa Barbara, and other places, there are extensive but shallow 
lagoons, separated from the ocean by a narrow, canal-likechannel. Such places, on being filled 
from the sea at high water, may be shut off, and the water then be allowed to evaporate by 
