380 
The American Geologist. 
June, 1896 
albitite. Other dikes in the immediate neighborhood of the 
albitite dikes contain quartz in addition to the feldspar, form¬ 
ing a soda-granulite, as the term is used by Michel Levy, or a 
soda-aplite, following Rosenbusch. In the serpentine area of 
G-rizzly hill (Bidwell Bar sheet) are numerous dikes of a soda- 
granulite containing muscovite in addition to the quartz and 
albite (see No. 725, S. N., table of analyses.) 
There are also numerous soda-feldspar dikes northwest of 
Meadow valley in serpentine by the trail to Rich Bar. Those 
noted were chiefly finer grained than the dikes above men¬ 
tioned. 
The large serpentine area to the southeast of Meadow valley 
that contains the soda-feldspar dikes above mentioned is 
flanked for considerable stretches by areas of a coarsely 
fibrous dark green hornblende-schist. One of these masses 
lies on the west flank of Clermont hill. In it are veins of a 
peculiar blue quartz. (No. 458 Plumas.) Another area is 
crossed by the south fork of the Feather river to the east of 
Little Grass valley. In it are dikes of a coarse grained rock 
(No. 97 S. N.) composed of a very white feldspar, pretty cer¬ 
tainly albite, and the same peculiar blue quartz that occurs 
without any feldspar in the hornblende-schist of Clermont 
hill, suggesting a genetic connection between the blue quartz 
veins, and the soda-granulite and soda-syenite dikes just des¬ 
cribed. The hornblende of the schist is an aluminous variety, 
containing about 48% of silica. 
In another paper* altered porphyry dikes composed chiefly 
of albite were described as forming the lodes of the Shaw and 
Orofino mines (the latter now called Big Canyon mine) in 
Eldorado county (Placerville sheet). In the table of analyses 
No. 452 S. N. is an analysis of the Shaw mine dike. 
The feldspathic nature of the Shaw mine lode was sugges¬ 
ted by Mr. C. A. Aaronf in 1892. This article was not refer¬ 
red to by the writer in the paper in the American Journal of 
Science, as it was not then known to him. A portion of Mr. 
Aaron’s article is here quoted, to give a better idea of the 
economic value of the lode. 
*Am. Jour. Sci., 3, vol. xlvii, 1894, pp. 470-471. 
fEng. and Min. Jour., November 19, 1892. 
