48 Schoolcraft’s Localities. 
erystals of brown, or yellowish-brown foliated gypsum, va- 
riously grouped. 
Compact Gypsum.—At Sandusky Bay, Ohio. This 
gypsum forms a continuous stratum extending horizontally, 
from the flat shore of the lake, near the Light House, into 
the bed of lake Erie. It is situated so low as to be entire- 
ly covered by the water during the prevalence of easterly 
winds. It is of a uniform white colour, with a fine close 
grain, and its surface presents very minute glimmering fo- 
lia. It yieldseasily to the knife, or can be turned in a lathe, 
and is sometimes so compact and hard as to take a polish. 
These varieties may be considered a gypseous alabaster. 
Some attempts have been made to convert this material in- 
to inkstands, and other utensils. It has also been ground 
for agricultural purposes, and if found to answer expecta- 
tion, may become an article in the commerce of the Lake. 
Smoky Quartz.—At point Keewiiweenon,* Lake Supe- 
rior, M. T. In a crystaline mass, associated with ame- 
thyst. This mass separates with a blow of the hammer, 
falling into innumerable translucent, dull crystals deeply 
striated across the lateral , and inated 
by smooth six sided pyramids. The colour is not equally 
intense, but often appears in clouds, and is sometimes in- 
termingled with the violet hue of the amethyst. 
Amethyst—With the preceding. Its colour passes from 
violet to purple, and is seldom uniformly diffused. It is in- 
timately counected with the preceding variety, and the 
colours so mingled, in some pieces, as to make it difficult to 
determine to which subspecies they ought to be referred. 
‘say subspecies, because, it would seem, from this connex- 
ion, that the former is entitled to that destinction as well as 
the latter ! 
Greasy Quariz.—At the Sauit de Ste. Marie, County of 
Michilimackinac,Mich.Ter. In detached fragments, white, 
opaque, laminated, and possessing the peculiar fatty lustre. 
Mil artz.—With the preceding. | Neither of these 
varieties has been traced in situ. I suppose them to be- 
to the primitive ranges along the north shores of lake 
perior. 
~ 
*Called Keweena in my Nar. Jour. and upon the maps of Sir Alex. Ma- 
Kenzie. Theabove pronunciation is taken from the Chippewa Indians 
who inhabit the country. The double vowels are caleulated to convey 
their long sounds. 
