798 HENRY S. WASHINGTON 
rence with quartz would be certainly very anomalous. Aegirite 
also, mentioned by Sears, was wanting in the material examined 
by me. 
An analysis was made of a nearly fresh, typical specimen col- 
lected from a newly blasted mass on Prospect street, Gloucester. 
It is neither extremely light nor extremely dark in color, and 
seems to be an average sample of these rocks. Its sp. gr. was 
2.612 at 17° C. For comparison there is given in I] the analysis 
of an acid akerite from Norway. 
I II I II 
SiO, ee OOK OO 66.13 Mic Ol) tia Ong 0.04 
Mi@ se 2a 0.76 0.74 CaOresn ss es DPI 0.81 
NI Oe SE OS 17.40 BAO) sa = 5 MOE Paes 
enOr = Oe 1.07 2.19 Na,O Se ee 4.03 5.28 
FeO So a ee A Bits: eNO hoe tor ea Be 5.60 
IMbMO) Ss = 1s trace 0.13 lal Oolitic hi lec 0.41 1GQ2 
100.33 99-54 
I Akerite. Prospect street, Gloucester. H.S. WASHINGTON, anal. 
II Akerite (porphyritic). Between Thinghoud and Fjelebua, Norway. MAUZELIUs, 
anal. BROGGER, Zeit. Kryst., Vol. XVI, p. 46, 1890. 
It will be seen that this analysis, which closely resembles 
that of the enclosure in granite, except the higher lime, is 
essentially that of a basic granite or an acid syenite. In this case 
I adopt Brogger’s scheme of classification,’ and consider that 
the limit between the syenites and the granites lies at the silica 
content of the prevailing feldspars, which are here orthoclase 
with about 66 per cent. and albite with about 68. These rocks, 
therefore, I would class with the quartz-bearing augite-syenites, 
in accordance with Wadsworth, Sears and Rosenbusch. 
That the rock belongs to an alkali magma is evident from its 
high alkali content (K,O0 + Na,O—9.45), and its close par- 
allelism with the more acid of Brégger’s akerites is shown by 
comparison with the analysis in I]. It must be noted, however, 
“that this is an extreme type, and that the akerites as a group 
are more basic. Probably some of the darker and presumably 
BROGGER, Zeit. Kryst., Vol. XVI, p. 55, note, 1890. 
