JD. Dana—Note on the Bernardston Helderberg Formation. 885 
common ; staurolite ; green and black hornblende; orthoclase; 
garnet; along with pyrite, magnetite, and granular limestone. 
The mica slate and schist and the staurolitic mica slate are 
not distinguishable from kinds that are of earlier age. 
e hornblende rocks are peculiar. Those which are made 
mainly of hornblende have a dark green color, and are massive, 
often indistinct in bedding instead of schistose and» muc 
or quartzyte and orthoclase. 
he whitish quartzytic syenite mentioned on the preceding 
quartz grains with few of feldspar. 
e gneiss also is peculiar. It generally consists very 
largely of grains of quartz, even where looking to the eye like 
a true gneiss. The mica is almost solely the brown kind and is 
like that of the mica slate, though often seeming to have as little 
elasticity as chlorite; and the regular disposition of the spots 
of mica, give to the most quartzytic varieties a strikingly 
guneiss-like look. Professor Hitchcock refers the rock to the 
Bethlehem gneiss. But “the most characteristic of the rocks 
comprising this formation,” he says, speaking of the Bethlehem 
gneiss, “is a reddish granitic gneiss, the flesh-colored orthoclase 
predominating, with chloritic or some hydro-micaceous mineral 
of orthoclase in characteristic “ Bethlehem gneiss” which renders 
connection with a Helderberg formation improbabi 
The quartzyte in some places—as two miles west of South 
Vernon,—contains much pearly mica (hydrous mica?); a 
weathered surface of such a specimen shows that the rock 
consists mainly of quartz. In other places the quartzyte is 
marked with dark-gray and blackish lines where the mica is 
not distinguishable without a glass, of it indicates by its 
fineness of texture, and sometimes even flinty aspect, that the 
quartz sand of which it was made was very finely comminuted, 
-and not coarse like that from which the Green Mountain 
Am, Jour. 8cr.—THIrp ce % Vou. XIV, No. 83.—Nov., 1877. 
