Camptonite Dikes, Etc. — Marsters. 
101 
as first described by Hawes.' Similar ones have been subse- 
quently brought out by Harrington ^ and Kemp.' J. J. H. 
Teall ' has also described a dioritic type of rock which forms 
dikes piercing qnartzites and limestones in the Scottish High- 
lands. From the description we pliould infer that it is similar 
to the Camptonites. Slides from all of the American localities 
have been compared in the preparation of this paper and they 
are strikingly alike. They have also been compared with 
slides of nearly all the other dikes so far described in this 
country, chips or slides from which have in most cases been 
kindly given or loaned by their describers.'^ As compared 
with these they are diflerent and individual. It is therefore 
here advocated that the name Camptonite be restricted to dike 
rocks consisting especially of brown basaltic hornblende in 
rod-shaped crystals, and of plagioclase and magnetite, together 
with which augite may or may not be associated. 
Camptou, 
Forest of 
Fairhaven. 
Proctor. 
N. H. 
Montreal. 
Dean, N. Y. 
(Kemp.) 
(Kemp.) 
(Hawcs.) 
(Harrington) 
(Kemp.) 
SiO., 
43.5 
41.0 
41.94 
40.95 
48.19 
Al, 6:, 
17.02 
21.36 
15.36 
16.45 
16.79 
Fe, 0:. 
13.68 
13.44 
3.27 
13.47 
18.37 
FeO 
9.89 
MnO 
0.25 
0.33 
Ti 0. 
4.15 
3.39 
Ca 
8.15 
10.4 
9.47 
10.53 
6.85 
MgO 
(5.84 
3.85 
5.01 
6.10 
1.32 
Kro 
3.02 
1.31 
0.19 
1.28 
1.11 
Na, 
2.84 
2.86 
5.15 
4.00 
5.59 
P.O5 
0.29 
Co, 
2.47 
Lossonlgn. 
4.35 
5.00 
3.29 
3.84 
2.31 
Total, 
99.40 
99.22 
100.44 
100.63 
100.53 
The writers purpose during the coming summer to study 
the dikes recorded as so plentiful near Burlington, Vt., and to 
establish in connection with them such further typical fea- 
' A)i\. Jour. Set. (m) vol. ,\vii, p. 147. 
■-• Geol. Sur. Canada, 1877-78, p. 439. 
^Am. Jour. Sci. (in) vol. xixv, p. 3.31, 1888. Am. Xaturalist, Aug. 
1888. 
*Geol. Magazine, 1886, p. 346. 
* Emerson. Franklin Furnace mica-diaba.se. ^»i. Jour. Sci. (in) vol. 
XXIII, p. 376-380, 1S82. Haworth, Miss<niri dikes. Am. Geol.. May- 
June, 1888, Hobbs. Sumnierville dike, Hart. Bull, ivi Xo. 1, and 
others. 
