and its associates on Lake Superior. 193 
lamin of the latter showing ruby-red reflections. Its specific 
gravity is 2°81, and the smallest trace only of its powder is 
attracted by the magnet.” He considers the mineralogical com- 
position of this rock to be 
Delessite, eS AO'UD 
Tee ss ..- 20°00 
Labradorite, -------- 40°00 
100°00 
The rocks, to which the above given analyses refer, are repre- 
sentatives of the three predominating types of the trap of 
2°65 
Although the name melaphyr is an unfortunate one, having 
been first used to designate an entirely different rock, an hav- 
under consideration. “All the trap rocks and associated amyg- 
daloids of Portage Lake are varieties of melaphyr. 
tphism, in which the chlorite resulted, largely or wholly, 
m the alteration of hornblende or pyroxene. In the more 
ish-gray. It contains generally grains 0 
Small tabular crystals of specular iron. aes 
2 inée-grained ; the constituents, light-green or see vie 
clinic feldspar and dark-green delessite, are nage ania stp 
= le, but more generally they are not so. The usu “to “a 
q <j grayish-creen, but it sometimes is speckled with brown 
