72 
MUSEUM BULLETIN NO. 27 . 
In view of the very compact and almost amorphous condition of the 
material from the Union pit, and also to a lesser degree of the matrix of 
the old Standard mine specimens, with the consequent uncertainty 
as to the constitution of the material selected for analysis, it has not been 
deemed advisable to assign special names to these substances. Even 
in the Union pit specimens, which have an extremely compact structure 
like chalcedony, it is usually possible to see some small glistening flakes of 
colerainite distributed through the material, and sometimes these are 
arranged in very narrow streaks. When crushed and examined in oil 
under the microscope, the fragments are found to be all perfectly trans- 
parent, with low index of refraction, and for the most part they are 
weakly birefringent with a concentrically banded spherulitic structure; 
occasionally also, a flake is found which gives the uniaxial positive inter- 
ference figure. Other fragments, however, appear to be perfectly isotropic 
and amorphous. It is believed that the crystalline material is in all 
cases colerainite, and that there is probably associated with this some 
amorphous hydrous magnesian silicate, perhaps also aluminous, of 
indefinite and possibly variable composition. In some cases the latter 
may have a composition approaching that of pseudophite or loganite, 
and in others near serpentine. 
Although the colerainite specimens, both from the old Standard 
mine and also from the Union pit, were collected from dumps, and the 
material was not actually seen in place, it doubtless originally formed 
veins traversing the massive serpentine in each case; and, judging by the 
size of the specimens, especially those on the old Standard mine dump, 
these veins must have had a width of 2 or 3 feet at least, and may have 
been very much wider than this. As has already been stated, examination 
shows that this vein material is composed almost entirely of colerainite 
alone, with probably some associated amorphous hydrous magnesian 
silicate. The mode of occurrence would thus be very similar to that of 
the veins or dykes composed of other minerals, such as diopside and 
vesuvianite, which have been noted at several localities and described 
in earlier pages, and it is believed that the colerainite veins have originated 
in a similar way to them. The conclusions arrived at by the writers 
regarding the genesis of these various mineral veins have been set forth 
in a section dealing with the origin of the minerals (page 10). Briefly 
stated, it is believed that the extremely acid and aqueous granitic magma 
which formed the last phase of intrusion of the igneous rocks of the 
serpentine belt, acted as a powerful solvent on the basic rocks as it was 
injected through fissures traversing them; this solvent action being 
largely due to the extreme difference in chemical composition between 
the magma and the invaded rocks. As a result, the magma, or the 
magmatic residue, was enriched in certain constituents derived from 
