230 FieLp CoLumBian MusrtuM—GEOLoecy, VOL, I. 
similar to those previously described. The color of the crystals of 
all types varies from a pale yellow to a deep orange. Some are per- 
fectly transparent, but the majority are translucent to opaque. The 
yellow color is probably due to the presence of iron, as on heating 
the crystals turn black and become slightly magnetic. Other quali- 
tative tests likewise indicate the presence of considerable iron. 
DOLOMITE USED AS INDIAN MONEY. 
NEAR LAKEPORT, LAKE COUNTY, CALIFORNIA. MUSEUM No. M6387. 

Specimens of dolomite from the above locality, and of the 
‘¢money’’ made from it, were collected by Dr. G. A. Dorsey, Curator 
of Anthropology of the Museum, during a visit made in 1889 to the 
Pomo Indians, a tribe of the Kulanapan stock who inhabit the region. 
The material has long been used as a medium of exchange among 
these Indians, but I cannot learn that it has been hitherto described. 
The mineral occurs in the form of nodules, or boulders, roughly 
oval in shape, and from four to eight inches in diameter. They are of 
a rusty yellow color upon the surface and the local Indian name for 
them, /Pol'-ka-be, means rusty color. A freshly fractured surface 
shows a pure white color, except for occasional rusty seams, and 
lustre like that of unglazed porcelain. ‘The texture is compact and 
fracture flat conchoidal. A determination of the specific gravity of a 
pure white fragment gave G. = 2.878. Dr. Dorsey did not visit the 
mine whence the dolomite is obtained, but was informed that it was 
situated on the east shore of Clear Lake, a few miles southeast of 
Lakeport. 
While the mode of occurrence cannot be stated with certainty, 
it is probable that it is as residual boulders in a reddish clay. 
A partial analysis by the writer gave CaO, 28.27%, Mg O, 
22.46%, and Fe O, 1.18%. These percentages are nearly those of 
a typical dolomite. | 
The use of the mineral by the Indians as a medium of exchange 
is a long established custom, and the value at which they esteem a 
well worked piece is nearly equal to its weight in gold. In order to 
make the money, symmetrically shaped cylindrical pieces are cut out 
from the crude boulders. These are burned and the burning brings 
out reddish streaks of color doubtless from oxidation of the iron, 
