Dikes Near Lyon ML, X. Y. — Eakle. 35 
Chlorite appears as the first stage in the decomposition and 
from thence has passed into epidote. In many crystals the 
original crystallographic form is preserved and the sections 
are broken up into rods of epidote, often in parallel arrange- 
ment. The amount of epidote is exceptional to the diabases 
of this region, as very little has been noted in the other 
dikes.* 
Analyses of diabases are placed below. Those in columns 
I and IV are of dikes 2 and 3, respectively. Columns II and 
V contain ana^ses by Kemp, and column III by Leeds. 
Eakle. 
I. 
Kemp.* 
II. 
Leeds.| 
III. 
Eakle. 
IV. 
Kemp.^ 
V. 
SiO 
44.51 
45.46 
43.41 
50.89 
51.93 
M fi% 
19.99 
19.94 
19.42 
15.39 
18.13 
Fe o° 3 
7.22 
15.36 
5.72 
5.77 
8.92 
FeO 
6.69 
CaO 
8.15 
8.32 
9.11 
8.75 
9.82 
MgO 
8.11 
2.95 
5.98 
7.60 
5.30 
K 2 
2.60 
3.21 
0.47 
2.72 
1.42 
Na.,0 
5.24 
2.12 
4.39 
5.67 
4.:'.4 
TiO 
0.35 
co; 
2.00 
Loss 
2.93 
2.30 
3.00 
2.46 
1.42 
98.75 99.66 100.54 99.25 101.28 
No epidote is found in dike 3, the green mineral being en- 
tirely olivine. Most of it is serpentinized to some extent, 
but a few idiomorphic crystals remain comparatively fresh 
and show forms similar to those cited on the augite crystal-. 
The several oxides of iron, magnetite, hematite, and limonite, 
are abundant from its alteration. The index of refraction is 
high and the double refraction strong. 
The dikes occurring inland do not differ essentially from 
dike 3 and may be cited as typical diabases. Some of them 
have their crystals prevailingly idiomorphic, with augite in 
excess. Such rocks have been called augite-camptonites by 
Kemp.§ There is a very striking similarity, in structure and 
mineral constituents, existing between these diabases and 
*Kemp, J. F., and Marsters, V. F. Trans. N. Y. Acad. Sci., xi, p. 13, 1891 
tLeeds, A. R. Notes on the Lithology of the Adirondacks. 30th 
Ann. Rep. N. Y. State Mus., p. 102. 
JKemp, J. F. On Dikes near Kennebunkport, Me. Am. Geolooist, 
Mch., 1890, p. 129. 
§Ibid. 
