4 List of Minerals and Organic Remains. 65 
spar; the radiating fibres passing * the circumference in- 
sensibly into calc. spar. It is very handsome, and is almost 
identical with the Italian zeolite. White fibrous zeolite is 
not uncommon in the druses of the Trap Mountain of 
siento, associated with tables of feldspar, pyrites and 
abasie. 
Stilbite.—In the amygdaloid of the north shore of Lake 
aokincn It is red, pecpey crystallized, encrusting 
nodules of cale. sj d lining druses. It occurs likewise 
in the conglomera erstratified with the amygdaloid. 
h aie | Mountain, ina druse with zeolite; 
form well i n jor perhaps originally greyish white. 
onder this name, ies been also recognized by Dr. Troust 
_ andothers, of Philadelphia. It is a pale flesh-red feld- 
spar, largely crystallized, and rc part of a vein of 
a porphyritic granite of great size, traversing gneiss. It is al- 
most every where full of brilliant. golden points, whichspar- 
kle with increased force, if held in particular lights. ‘This 
porphyritic granite prevails greatly in large contempora- 
heous masses, and wandering veins, in all the sienitic (or 
rather granitic,) districts of Lake Superior; but is most 
abundant in the gneiss of Lake Huron, and of Lakes La- 
croix and Laplarie, in 92° 20’ and 93° west longitude, and 
north from Lake Superior. This gneiss is of imperfect or 
sores stratification; full of hornblende in beds, lamina, 
also disseminated. It seems to belong to the transition, 
or are the younger of the primitive roc ocks ; judging from its 
constant Proximiby to red sandstoae, the oldest organic 
limestone, and to 
ere the he eaeee occurs, the gneiss is atraiaed in 
large « bold curves, which often run into knots of con- 
centric layers, many yards broad; but its Rases. course 
is N. W., N. N. W. of N. by W. with a corresponding eas- 
terly dip. Very frequently it passes into a granite. 
eagy Feldspar.—Lake Superior, in pitchstone porphy- 
In Lake Huron, and Gun-flint Lake, in greenstone 
porphyry. In Lakes Superior and Huron, they are splen- 
dent, transparent imbedded four sided prisms, of a pale 
wine-yellow color, Jo Gun-flint Lake, they arein six sided 
Pris dan halfinches 
OUI thas 
be 
Vou. VIL—-No. 9 
