428 REPORT ON NATIONAL MUSEUM, 1886. 



(4) PORPHYRIES OF THE VARIOUS STATES AND TERRITORIES. 



Inexhaustible quantities of porphyries of a variety of colors and great 

 beauty occur at Saugus, Maiden, Lynn, and Marblehead, and other lo- 

 calities in eastern Massachusetts, but which have never been utilized 

 to any extent owing to the cost of working. Many of these are of ex- 

 ceptional beauty, presenting colors red as jasper, through all shades of 

 pink, gray, and even black, often beautifully variegated and brecciatcd 

 in a variety of colors. Flow structures caused by the onward flowing 

 of the rock while in a partially cooled condition often gives rise to a 

 beautiful banding and interweaving of colors impossible to describe, and 

 which must be seen to be appreciated. The striking beauty of this flow 

 structure is sometimes heightened by the presence of angular fragments 

 of variously colored portions of the rock, which, becoming broken from 

 the parent mass, have been imbedded in a matrix of quite different 

 color, as at Hingham, where we have found bright red fragments im- 

 bedded in a yellowish paste. The rock acquires a beautiful polish, and 

 the fact that it has not ere this come into more general use is a sad 

 comment upon the taste of our wealthier citizens. Nearly as inde- 

 structible as glass, and as beautiful as an agate, and yet almost wholly 

 ignored except for purposes of rough construction. 



A large variety of porphyries, varying in color from black to red, oc- 

 curs also in New Hampshire, particularly near Waterville, some of 

 which would make fine ornamental stones. At Franconia, in the White 

 Mountains, there occurs a porphyry conglomerate formed of fragments 

 of jasper red porphyry closely cemented into a compact rock, which is 

 particularly beautiful. Slabs of this stone in the National Museum can 

 not be excelled for richness of color. 



Porphyries are abundant in many other States, but are scarcely at all 

 used. Maine, Pennsylvania, Missouri, Minnesota, and Wisconsin all 

 contain good material, though, as little or no search has been made for 

 the highly ornamental varieties, it is impossible to say what they can 

 produce. 



At Green Lake, in the last named State, there occurs a beautiful 

 stone of this class, almost black in color, with white porphyritic feld- 

 spars. It has been quarried, to some extent near the town of Uttny, 

 and polished columns of it may be seen in the German- American Bank 

 building and Union Depot at Saint Paul, Minn. It is greatly to be re- 

 gretted that no economic method of working so beautiful and durable 

 a material has as yet been discovered. 



Near Charlotte, in Mecklenburgh County, N. C, there occurs a very 

 light colored, almost white, quartz porphyry, which is penetrated by 

 long parallel streaks or pencils of a dead black color. These are so ar- 

 ranged that, when cut across, the surface appears studded thickly with 

 roundish and very irregular black points of all sizes up to half an inch. 

 Cut parallel with the direction of the pencils, the surface is streaked 



