436 A. P. COLEMAN 
parison of columns I and III, the latter being more basic, con- 
taining less alumina and alkalies, and far more lime and magnesia. 
It corresponds fairly well, however, to the composition of nephe- 
line syenite, the only important difference being in the amount 
of water. The syenite from Dalarne, whose analysis is given in 
column II of the table, having its nepheline weathered to a 
hydrous mineral, resembles this rock closely in composition, the 
only important difference being the larger percentage of soda. 
In their unusually low specific gravity, 2.46, also the two rocks 
are alike. 
One naturally expects to find the dike containing the rock 
above described in connection with some boss of nepheline 
syenite; but the slight examination hitherto made of the region 
by Dr. Bell and myself has not disclosed any area of that rock. 
If the analcite rock of Heron Bay had a granular texture, it 
would appropriately be named analcite-syenite, after the analogy 
of nepheline-syenite; but its peculiar structure of spherical 
groups of orthoclase embedded in a ground of analcite contain- 
ing radiating bundles of plagioclase laths and aegyrite needles 
sets it quite apart from the syenites. It will probably be wise 
to give it a separate name, and Heronite, from the name of the 
locality where it occurs, is suggested as suitable. 
Heronite may be defined as a dike rock consisting essentially 
of analcite, orthoclase, plagioclase, and aegyrite, the analcite 
having the character of a base in which the other minerals form 
radiating groups of crystals. The analcite clearly represents 
the magma left after the crystallization of the embedded min- 
erals; and it is evident that it can be formed only froma magma 
highly charged with water, and therefore under pressure. It is 
equally evident that Heronite, like other analcite rocks, cannot 
be an effusive, since under those circumstances the water would 
escape ;* and that its nearest relatives among effusive as well as 
plutonic rocksare to be found in the group containing nepheline. 
A. P. COLEMAN. 
*Cf. Pirsson, Analcite Group of Igneous Rocks, Jour. GEOL., Vol. IV, No. 6, 
pp. 686-688. 
