. 
of New-York and New-Jersey, &c. 183 
feldspar cannot readily be distinguished from quartz in a 
aewly broken specimen of this stone as from irregular crys- 
talization it does not present the fracture characteristic of 
eldspar, but where the surface has been long exposed to 
the air, the feldspar whitened by commencing decomposi- 
tion, is apparent. The 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. 
‘Lhe 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- 
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 
rom Staten-Island. In these precipices I have noticed 
ne 
proaching the character of kaolin ; it is pulverulent, and of 
2 grayish white, and does not form a paste with water. * It 
‘and by Dr. Torrey to whiten and fuse when exposed 
to heat ; it appears to be a suitable material for the manu- 
mountain bordering the river, in many places, secondary “i 
gillaceous shist, conglomerate, red, white, yellow and pur-_ 
