of New-York and New-Jersey, Se. "188 
feldspar cannot readily be distinguished from quartz in a 
newly broken specimen of this stone as from irregular crys- 
talization it does not present the fracture characteristic of 
feldspar, but where the surface has been long exposed to 
the air, the feldspar whitened by commencing decomposi- 
tion, is apparent. ‘lhe summit rock of the Palisado range 
is not so dark as the greenstone of New-Haven, having less 
hornblende but otherwise agreeing in external character and 
geological relations. 
The only interesting crystalized mineral associated with 
the greenstone of this range is prehnite. I have recently 
discovered good specimens of that mineral in ledges of fine 
grained greenstone that border the eastern shore of New- 
ark bay—for several miles, masses of radiated prehnite of 
a lightish green were of frequent occurrence, some of 
them a foot in diameter. I found at this place a detached 
specimen of compact prehnite five inches in thickness, 
weighing six pounds—it was ascertained by Dr. Torrey to pos- 
sess the uncommon specific gravity of 3145. Coarse green- 
stone in place is observed within a short distance of Bergen 
point—it forms the nucleus of hills of considerable eleva- 
tion five miles below the -village of Bergen. Mural preci- 
pices of coarse greenstone, gradually diminishing in alti- 
tude border the eastern section of the peninsula to within 
half a mile of the narrow sound that separates New-Jersey 
from Staten-Island. In these precipices I have noticed 
erystalized feldspar filling fissures halfa foot in breadth. In 
ihe vicinity of Wehawk, on the eastern face of the moun- 
tain, greenstone of a dark color and fine grain, in which 
hornblende greatly predominates is often observed. In this 
neighbourhood I have recently discovered a mineral ap- 
proaching the character of kaolin ; it is pulverulent, and of - 
a grayish white, and does not form a paste with water. It 
was found by Dr. Torrey to whiten and fuse when exposed 
to heat ; it appears to be a suitable material for the manu- 
facture of porcelain ; it is associated with a secondary dis- 
integrating rock of quartz and decomposing feldspar ; the 
kaolin originates from this last mentioned mineral; this. 
rock is in various stages ef decomposition, is several feet in 
thickness and lies under greenstone. At the base of the 
mountain bordering the river, in many places, secondary ar- 
gillaceous shist, conglomerate, red, white, yellow and pur- 
