112 Mineralogy and Geology of the White Mountains. 
Trap and Granite Boulders, and Granite Veins. 
East of Centre Harbor, two and a half miles, are numerous 
fragments of large size, of trap in granite, but no dikes appeared ; 
some of dark blue, others of a reddish brown; a mixture of red 
feldspar and hornblende, mottled with dark spots; fracture con- 
‘choidal, and edges very sharp; strike fire with steel ; and others 
frequently met with in this region, composed of hornblende and 
feldspar, with an excess of the former, such as Saussure charac- 
terizes, judging from description, by the name cornéene. 
At four miles from C. H. are immense granite boulders, strewed 
for miles, and the exhibition of granite veins in them is truly re- 
markable. They are very numerous, usually fine grained, and 
much whiter than the rock; the regularity and parallelism of 
their sides is as exact as if drawn by art, seldom over a foot wide, 
and usually but a few inches, and less: sometimes a rock is cut 
from side to side by a vein, retaining the same direction and thick- 
ness throughout; sometimes by two veins, which are parallel, 
and again by several, running in every direction, intersecting each 
other, the older cut by the more recent. In the present state of 
our imowledge of the formation of veins, and especially of veins 
of the same composition as that of the tock containing them, 
whose sides present none of that irregularity common in dikes, 
an observer might almost hesitate to record facts that may add to 
the obseurity of the subject, were it not, that valuable general 
truths can be derived only from an extensive comparison of In- 
dividual facts. 
Dikes in Mouttonboro’. 
Two trap dikes, in sienitic granite, are found on the right of the 
road on the top of Rogers’ hill, one and a half miles from Moul- 
tonboro’ corners, towards Tamworth; course W. by N.; parallel, 
and both contain fragments of granite of considerable size. Fig. 4. 
No. 1; one foot wide; sends off a lateral branch which curves 
southerly ; eight inches wide. 
No. 2; three feet from the former, is two feet wide, and por- 
phyritic, with crystals of feldspar. 
Dikes in Tamworth. 
_ At Fort Jackson, in Tamworth, about four miles west of Things’ 
tavern, on the right of the road at top of a hill, fifty rods from 
Bear Camp river, is a small trap dike in granite, six inches wide ; 
course E. and W. 
