54 The Ainevican Geologist. juiy, 1892 
Anah'ses of samples from the olivine rock, dike (5 below the 
Androscoggin mill in Lewiston (39199), and the 12 inch dike 
from the cutting in the Lewiston and Auburn railroad in Auburn 
(28531) yielded Prof. Packard results as below. For purposes of 
comparison are given (iii) the analyses of dike No. 1, at Camp- 
ton, New Hampshire, as given by Hawes.* (iv) of the Montreal 
diorite as given by Harrington,! and (v) and (vi) camptonites 
from Proctor and Fairhaven, Vermont, as given b}' Kemp and 
Marsters. + 
I. 
II. 
III. 
IV. 
V. 
VI. 
SiOo 
39.32 
41.15 
41.63 
40.95 
41.00 
43.50 
TiO; 
1.70 
1.60 
3.95 
3.39 
AI2 0, 
14 48 
13.51 
13.26 
16.45 
21.36 
17.03 
Fe^ O3 
2.01 
2.32 
3.'9 
13.47 
13.44 
13.68 
FeO 
8.73 
8.63 
9.92 
Mn 
0.71 
1.28 
.27 
0.33 
CaO 
8.30 
8.75 
8.86 
10.53 
10.40 
8.15 
MgO 
11.11 
10.09 
7.31 
6.10 
3 85 
6.84 
K, 
0.87 
1.22 
3.32 
1.28 
ISl 
2.84 
Na, 
3.76 
3.21 
2.49 
4.00 
2.86 
3.84 
P.O5 
0.61 
.61 
0.29 
COo 
5.25 
5.54 
5.20 
HgO 
2.57 
3.05 
1.35 
(Ign)3.84 
5.00 
4.35 
99.42 100.96 100.75 100.63 99.22 99.40 
From the al)Ove it appears that in the immediate vicinit}' of 
Lewiston and Auliurn are two series of small and geologically 
speaking insignificant dikes, both having essentially the same 
trend (so nearl}' so that they were supposed at the time these 
observations were made, (1883), to belong undoubtedly to the 
same system) one of which is normal diabase while the other, in- 
cluding nine or more lying almost within the southern outskirts 
of the two cities, must be referred to the lamprophj'rs, or if a 
specific name is demanded, may be called camptonites as the 
term is used by Rosenbusch. There are objections to this. In 
all of them augite occurs both as phenocrj'sts and as a constituent 
of the groundmass, and must be considered as of greater genetic 
importance than the hornblende. There is moreover an almost 
constant tendency toward an ophitic structure as displayed in 
basalts and diabases. 
Just how much weight in the matter of classification is to be 
attached to micro-structural features, it is perhaps as yet too 
*Am. Jour. Sci., 3d, xvii, 1879, p. 147. 
tRep. Geol. Survey of Canada, 1877-78, p. 44 G. 
JTrans. New York Academy of Science, vol. xr, 1891. 
