Study of the New York Obelisk as a Decayed Boulder. 97 



tains, on the east side of the river, a short distance above the present 

 village of Assouan, lie the old quarries of Sun-t ("Entrance giver") 

 of ancient Egypt, which yielded the so-called "oriental granite," 

 •'syenitic marble," or "Thebaic Stone," out of which nearly all 

 obelisks and colossi were cut. This was the " machet" or "niahet," 

 " heart-stone," of the old Egyptians, so-called, it may be, on account 

 of its hardness and durability,^ perhaps in connection with its bright 

 red color. For the same reason, on account of its flame-colored 

 crystals of microcline, the Greeks afterward called it pyropoecilo7i, 

 the fire-variegated stone. 



1. 3Iineral constitution of Syene granite. 



According to the observations of Russegger, as Prof. Alfred 

 Stelzner states : 



"The structure and composition of the 'Oriental granites' are 

 very variable. Coarsely granular varieties, made porphyritic by 

 microcline^ crystals, which are distributed without regularity in the 

 main mass, seem to be the most usual. They occur immediately in 

 the neighborhood of Syene (Assuan). Out of these are developed 

 locally (for instance, on the road along the cataracts of Syene) such 

 coarsely granular masses, that the individual feldspar and quartz 

 constituents reach the size of a cubic foot; in other places, the size of 

 the grains diminishes, and then there results, by a parallel arrange- 

 ment of the flakes of mica, a gneissoid rock. Among the varieties 

 of composition three are especially given. That which seems to be 

 most widely distributed is an amphibole-granite, containing biotite, 

 in the composition of which microcline,^ oligoclase, quartz, amphi- 

 bole, and biotite take part. Some of the principal localities for this 

 are the old quarries near Syene, and, besides this, Djebel Gareb and 

 Djebel Ezzeit. This principal rock, by the gradual diminution of 

 its hornblende, either merges into normal biotite-granite, which may 

 be either rich in mica (east side of the hill on which the town of 

 Syene is built) or poor in mica (Debu); or it passes, by disappear- 

 ance of its quartz and the predominance of its hornblende, into nor- 

 mal syenite." 



Bv the last term, Stelzner refers to the combination of microcline 

 (or of orthoclase) with hornblende, free from quartz, to which the 

 German petrographers now confine the name syenite. The por- 

 phyritic hornblendic granite of the old quarries of Syene varies also 



1 Leuormaiit, op. cit., 25. ^ Frazer, loc. cit., 367. 



