KINDS OF ROCKS. 445 
I. NOT CONTAINING NEPHELITE, 
1, Syenyte. Quartz-Syenyte.—A granitoid rock consisting 
of hornblende and orthoclase, with or without quartz. 
Some oligoclase is often present. ‘The quartziferous va- 
riety, or quartz-syenyte, includes the syenyte of the obe- 
lisks and pyramids of Egypt. Like that, the rock 1s often 
flesh-colored ; but whitish and grayish varieties are also 
common. . ‘The Saxon syenyte, without quartz, afforded 
Silica 59°83, alumina 16°85, iron protoxide 7-01, lime 4°43, 
magnesia 2°61, potash 6°57, soda 2°44, water 1°29, and G= 
2:75-2:90. Metamorphic and eruptive. Similar varieties 
occur under both divisions of syenyte. 
VARIETIES.—a. Porphyritic. b. Albitic ; containing albite in addi- 
tion to the constituents of true syenyte. c. Oligoclase-bearing. da. M- 
caceous ; containing disseminated black mica, which is usually bio- 
tite, and sometimes lepidomelane. e. Garnetiferous. {f. Hpidotic ; 
containing disseminated epidote. The gray ‘‘granite” of Quincy, 
Massachusetts, south of Boston, extensively quarried for architectural 
purposes, is a quartz-syenyte, consisting of orthoclase, black to dark 
green hornblende, and quartz, with some triclinic feldspar. Quartz- 
syenyte occurs also in the Frankenstein Cliff, five miles south of 
White Mountain Notch; also in Mount Chocorua, N. H.; in the Ar- 
chean of Canada, at Grenville, a red kind containing very little quartz, 
and a similar rock on Barrow Island, St. Lawrence, but containing 
much quartz and little hornblende. Syenyte without quartz is a rare 
rock in Eastern North America. It occurs in Nevada. 
The name Sycnitcs is used for this rock by Pliny, who adds that it 
was also called ‘* pyrrnopcecilon”—this appellation, meaning fire-red 
variegated, referring to its being brightly spotted with rose-red. The 
quarries in the vicinity of Syene (the modern Assouan), whence the 
Egyptians obtained this stone for their obelisks, columns, statues, 
sphinxes, sarcophagi, and the lining of their pyramids, are of great 
extent ; and in one of them there is an unfinished obelisk in its origi- 
nal position. They are situated to the south of Syene, and between 
that place and the island of Philoe. The rock consists chiefly of red 
feldspar and grayish quartz, with oligoclase, some black hornblende, 
nd a little black mica. An analysis by Delesse obtained Silica 
70°25, alumina 16:00, iron oxide with some manganese 2°50, lime 1°60, 
expelled on ignition 4°65, magnesia and alkalies by loss 9:00—100. 
More remote from Syene the rock loses its hornblende and becomes 
a granite. 
The Scotch syenyte, so much used for monuments, is quartz-syenyte. 
It oceurs both red and dark gray, and the former is closely like the 
HKgyptian syenyte. 
Werner applied the name ‘‘syenyte ” to the quartzless syenyte of 
Plauenschen-Grunde, Saxony, an analysis of which is given above (a 
rock he afterwards called ‘‘ greenstone”). G. Rose used the term for 
the quartz-syenyte. Other German lithologists have followed Werner, 
calling the quartz-syenyte, hornblende-granite. It seems best to draw 
