PRIMARY ROCKS. 
541 
Hornblende rocA:. Extensive strata of this are found in the Highlands, which are well 
characterized. The most extensive one observed forms the middle of the southeastern face 
of the mountain first east of the valley of Long pond, in Warwick, This stratum is, perhaps, 
twenty-five rods wide. An extensive stratum also runs through the Forest of Dean, along 
the western margin of the white primitive limestone.* Magnetic iron ore is associated with 
this stratum in many places 
“In addition to what has already been remarked of the foregoing rocks, it should be further 
stated that the felspar is generally in a larger proportion than the quartz. The color of the 
quartz is white and bluish, or reddish white ; the mica is black, green, or intermediate shades 
of these colors; and the felspar white, yellow, red and greenish. The hornblende is black, 
grey or greenish. 
“ The minerals embraced in the foregoing rocks are numerous and important. First are 
the ores of iron ; all the magnetic oxides are found in them. They also contain adularia, 
fibrolite, kyanite, manganesian garnet, serpentine, mica, plumbago, sphene, red oxide of 
titanium, crystallized hornblende, epidote, tremolite, zircon, crystallized augite, tourmaline, 
coccolite, sahlite.”! 
7. Quartz Rock. 
Quartz forms numerous veins and intruded masses in the Highlands ; they may be found 
in every hill and mountain.' It was not seen forming extensive masses, with the exception of 
one, described by Dr. Horton in Orange county. Describing it, he says, “ In the town of 
Monroe is a bed of quartz. It is two and a half miles southeast of Greenwood furnace. Its 
northeast end only is visible. At this place it is four rods wide, and rises fifteen feet above 
the gneiss on each side. It is visible for more than twenty rods, and gradually disappears 
beneath the surface. The quartz is white and nearly opake, containing in many places pale 
green coccolite. 
8. Serpentine Rock. 
“ Serpentine is found in connection with the iron ore at O’Neil and Forshee mines. A 
large vein of this substance exists in Warwick, on the east side of Long pond; its breadth 
is unknown. It is exposed ten feet wide and fifteen feet deep; its color is dark oil-green, 
approaching black.”§ It occurs in numerous localities in small quantities, and is usually 
associated with the white metamorphic limestones, forming in many places the verd antique 
marble. Several of the localities have been described among the Metamorphic rocks. 
*■ This range continues with some interruptions and offsets, north-northeast to near W'est-Point. Iron ore is associated with 
it generally. 
t Third Annual Geological Report of New-York, 1839, p. 137. tibid. p. 137. § Ibid. p. 138. 
