UNSTRATIFIED PRIMARY ROCKS. 225 



and finished in the most perfect manner, with carv- 

 ed capitals, and cost 4000 dollars eacii. 



That variety of granite that contains hornblende 

 in the place of the mica, and known under the name 

 of syenite,* is found in abundance in the same neigh- 

 bourhood with the granites here mentioned, and is 

 itself almost as largely wrought as the true granite, 

 or triple combination of quartz, feldspar, and mica. 

 The Astor House in the city of New- York is built of 

 tbis stone ; and from the same quarry are obtained 

 a large portion of the doorposts, window-sills, cap- 

 stones, and foundation pillars of the buildings now 

 being erected in that city. The Washington Bank 

 in Boston, and the Bunker Hill Monument, are built 

 also of syenite. 



Porphyry, syenitic porphyry, and porphyritic green- 

 stone, abound in various places adjacent to the coast 

 of New-England, e^npecially to the north and south 

 of Boston. Near Lynn the porphyry assumes all 

 the dark purple and other tints, with the fine polish 

 of the best antique varieties ; and when ornamental 

 architecture shall be more cultivated in this coun- 

 try, this rock will doubtless be considered as of in- 

 estimable value. 



Syenitic porphyry, or a syenite with imbedded crys- 

 tals of feldspar, occurs plentifully in fine specimens 

 near Cape Ann ; and a rock splendidly ornamented, 

 consisting of a fine greenstone paste, with dissem- 

 inated crystals of greenish feldspar, and sometimes 

 called porphyritic greenstone, is found in large veins 

 traversing syenite not far from the same headland. 



* From Sienna, in Upper Egypt, whence were obtained the 

 well-known Egyptian monuments, such as Cleopatra's Needle, 

 Pompey's Pillar, Trajan's Pillar in Rome, &c. Many writers 

 describe the syenite as consisting of feldspar and hornblende. 

 The rock from Sienna is now ascertained to be a red granite^ 

 containing black mica and a small portion of hornblende 



s 



