1896.] Petrograp hy. 743 
Turner" gives a classification of the igneous rocks studied by himself 
from various places in California. He divides them into families in 
accordance with their mineralogical composition, including in the 
same family all those rocks with the same composition irrespective of 
structure. He then takes up the syenites and discusses them in some 
detail. The family is made to include syenites (granular), syenite-por- 
phyries (porphyritic) and trachytes (microlitic and glassy) and apo- 
trachytes. The syenites include soda-syenite or albitite, augite-syenite, 
hornblende-syenite and mica-syenite. The apo-trachytes include 
among other rocks Rosenbusch’s orthophyres and keratophyres. Until 
very recently no rocks of the syenite family have been proven to occur 
within the borders of the State. All those rocks described as such are 
now known to be hornblende-andesites, granites or diorites. The 
author refers briefly to the known occurrence of the syenites in the 
State and describes more fully some new ones. 
He reports dykes of white albitite-porphyries or soda-syenite porphy- 
ries in the rocks of the Mother lode quartz mines. In the bed of Moc- 
casin Creek the rock consists of quartz, muscovite and albite, but in 
other places it consists almost exclusively of albite with a few grains 
of an olivine-green mineral thought to be aegerite. The rock resem- 
bles somewhat Brégger’s sélosbergite and Palache’s albite rock contain- 
ing crossite. An analysis of one specimen gave : 
SiO, TiO, Al,0, FeO, FeO CaO MgO K,O Na,O H,O P,O, Total 
67.58 07 18.57 1.13 .08 .55 24 .10 11.50 46 .11 =100.34 
Gabbro-Gneiss from Russell.—The gabbro of Russell, St. 
Lawrence Co., N. Y., is said by Smyth’ to change its character rapidly 
in consequence of a variation in grain from moderately fine to very 
coarse, in structure from porphyritic to granular and in color from 
black to gray. Upon alteration the gabbro passes into a rock made up 
of red masses in a groundmass of gabbro. In other places it becomes 
schistose, when it takes on a granulitictexture. Sometimes hornblende 
is developed in it in long narrow plates that run approximately at 
right angles to the schistosity, causing the rock to resemble a metamor- 
phosed sediment. Even in the most gabbroitic varieties of the rock 
the plagioclase is changed into an aggregate of secondary products, 
among which scapolite is the most common. In the change of the 
massive gabbro into the schistose variety the constituents are first 
‘Ib. Vol. XVII, p. 375. 
7 Amer. Jour. Sci., Vol. 1, p. 273. 
