Notes on Some Rocks and Minerals — Emerson. 99 
pearance. A small vein of granular quartz runs across the 
slide containing highly refringent globules of small size 
with bubbles. See analysis II. 
The following analyses were made for me in the labor- 
atory of Amherst College, by Mr. Edward C. Smith : 
Analysis I. — Compact Banded Limestone. See page 98. 
Analysis II. — Green Hornstone. See page 98. 
I. 
SiO= 5.89 per cent. 
CO' 43.44 per cent. 
Fe=0^ 1.05 per cent. 
APO= 0.81 per cent. 
CaO 29 . 73 per cent. 
MgO 19.06 per cent. 
Total 99.98 per cent. 
II. 
SiCH 84.00 per cent. 
Fe^'O" 7.20 per cent. 
Al'O' 0.92 per cent. 
CaO ' . 4T per cent. 
MgO 1 . 07 per cent. 
Na'O 1.77 per cent. 
K'O 2 . 07 per cent. 
H'0 1.83 per cent. 
99.33 per cent. 
BASIC ERUPTIONS. 
Dioryte. — Port Foulke. A massive black rock with the 
shining jet-black hornblendes just visible to the eye, ani 
the plagioclase of glassy freshness. It has with the micro- 
scope the simplest dioryte-texture and the fieldspar is 
labradorite. 
Quirtz Diabase (Kongadiabase). This agrees closely 
with the rock from Rawdon, Quebec, figured in Rosenbusch. 
Gesteinslehre, p. 329. The rock is dull black with small red- 
dish spots. Flat blades of black aiigite sometimes a half 
inch long appear quite abundantly. They have a central 
suture and a transverse striation. These blades are found 
under the microscope to be wholly altered to a fibrous mass 
of dark green delessite which is quickly decomposed by acid 
