ee os eenish-gray feldspar, and reddish-brown mica, some of # 
192 ft. Pumpelly—Paragenesis of Oopper 
Although some peroxide is also possibly present, I have cal- 
culated the whole of the iron as protoxide, and have moreover, 
added the difference of the weight between it and the iron 
estimated as peroxide to the loss sustained by ignition, and put 
it dow ater. In this way the composition of the chloritic 
mineral, calculated to 100 parts, would be 
Silica, 31°78 
Adami oS eee. MA a I 15°47 
Protoxide of iron, = 98°87 
ime, peeuoe cies 9°64 
Magnesia, -- -- 4°37 
Water, .... 9°87 
100°00 
Delessite, ---- 46°36 
Labradorite, . ......_. 47°43 
xene or hornblende, 5°26 
agnetite, 0°95 
100°00 
By the same method of analysis, Mr. Macfarlane found the 
rock underlying the copper-bearing bed of the Quincy mine ® — 
consist of . 
Delessite in amygdules and grains,__ _- -- 38°00 
Labradorite, 62°00 
100°00 
This rock is distinctly amygdaloidal. ‘The matrix is fn® 
grained, but it is crystalline, and is seen to consist of differed! 
constituents. Its color is dark reddish-gray.” Its cavitil@ 
rarely the size of a pea, are filled with what seems to be the 
same chloritic mineral which occurs as a constituent of the’ 
rock above described. 
Mr. Macfarlane also examined the rock which overlies th? 
Albany and Boston conglomerate at the Albany and Bost? 
mine. “Tt is a fine grained mixture of dark green delessité, 
