G. W. Hawes—The Greenstones of New Hampshire. 185 
base is additional evidence of the sedimentary origin of these 
s; and they also confirm the view that the metamorphism 
was feeble in its degree, since it allowed of the preservation of 
these forms. It suggests, moreover, a source for the lime of 
the labradorite and other minerals of the rock, as well as for its 
pyrite and phosphate. Associated with these rocks are exten- 
sive beds of argillytes, which are scarcely altered. Everything 
points to quiet waters during the original deposition ; and finally 
to gentle metamorphism. 
4, Chlorite Schist. Metadiabase Schist.—Metadiabase, by the 
development of a schistose structure, becomes metadiabase 
schist ; or, as it is commonly called, chlorite schist. This rock 
Ch ee 
Binns ... eee 
Werle Oxide .... eae 2°58 
Ferrous Oxide... eS ebbing a ee 
Manganous oxide... -.... - sd ee. "25 
ime = ee ee) ee 
wernetisn: 8. oo as 6°67 
ash . Beart meee ee, “09 
ieee Greet) Ge ee ee ee 3°31 
Seanic acid... ac as "52 
Str ee 2°39 
100°42 
_ This rock which, as the microscope shows, contains but little 
titanic iron, yet has more than twelve per cent of oxides of iron ; 
and hence the analysis indicates a ferruginous chlorite contain- 
ing but little magnesia. The chlorite which best fulfills the 
conditions of composition and optical properties is the one 
Which occurs in igneous diabase—the diabantite ;* and which 
8 very apt to be formed in ferruginous rocks. If we consider 
ne water as an index to the amount of this chlorite, and the 
temaining magnesia to indicate pyroxene, we find that the rock 
Consists of 25 per cent of chlorite, 20 per cent of pyroxene, 1 
Per cent of titanic iron, and a residue nearly identical in com- 
Position with labradorite. These schists are sometimes highly 
* This Journal, vol. ix, June, 1875. 
