The crystals are generally transparent and frequently tinged yellow in
color. It gelatinizes by boiling with acid, and after intumescing before
the blowpipe, fuses to a frothy mass. To keep this mineral when in
crystals from crumbling upon exposure it may be dipped in a thin mastic
varnish or in a gum-arabic solution.
_Heulandite_.--This rare mineral has been found under the same
conditions as laumonite in Shaft No. 2, but it is seldom to be met with,
and then in small crystals. It is of a pure white color, sometimes
transparent. It intumesces and readily fuses before the blowpipe, and
dissolves in acid without gelatinizing. Hardness 4, specific gravity
2.2.
The few other minerals occurring in the tunnel are so extremly rare as
not to be met with by any other than an expert, and it is impossible
to detail the localities, as they generally occur as minute druses or
incrustations upon other minerals with which they may be confounded, and
have been removed as soon as discovered. The minerals referred to are
analcime, chabazite, Thompsonite, and finally, the mineral which I first
found in this formation, Hayesine, which is extremely rare, and of which
I only obtained sufficient to cover a square inch. The particulars in
regard to its locality, etc., maybe found in the _American Journal of
Sciences_ for June, page 458. I will now sum up the characteristics of
these several minerals of this locality in the table:
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