At Franklin garnet was one of the most abundant minerals found in the pegmatite
contact zones in parts of the ore body. Great masses of yellow, green, or
brown massive garnet, mingled with biotite, franklinite, rhodonite, calcite,
and other minerals, were characteristic especially of the Trotter and Parker
shafts. This garnet, which was all somewhat manganiferous, rarely occurred
in crystals, though here and there rough crystals were found embedded in
the calcite. The material analyzed and named "polyadelphite" by
Thomson (24) was probably of this nature.
Sharp dodecahedral crystals of black, brown, and yellow garnet embedded
in calcite have been recorded from Franklin but without definite statement
of locality. Abundant rough brownish dodecahedrons, some of them several
inches in diameter, were found with pyroxene in a pocket in limestone near
Double Rock and are illustrated in plate 11, A.
Some of the garnet was embedded in colorless sphalerite.
Small translucent raspberry-red and pale-yellow dodecahedrons, together
with massive granular garnet of the same colors, form a considerable part
of the specimens from the pockets at the Buckwheat mine in which were found,
among other species, the rare mineral pyrochroite. (See page
50.) This garnet is manganiferous, but sufficient material for analysis
could not be obtained, and the refractive index is that of andradite.
At the Gooseberry iron mine on Balls Hill there was opened at one time
a large pocket containing several bushels of garnet crystals of great beauty.
As seen in the Losey and Canfield collections these garnets are black, very
brilliant, large, and very symmetrical, being dodecahedrons with narrow
faces of the trapezohedron. One in the Canfield collection measures 23 inches
around a central section. They were associated with pyroxene, zircon, and
scapolite. Red and cinnamon-brown massive garnet were also found there with
magnetite. It showed but a trace of manganese, differing in that respect
from all the samples tested of garnet found near the zinc ores, which are
rich in manganese.
At Sterling Hill garnet is not so abundant as at Franklin. Dodecahedral
crystals of rough brown garnet, an inch or more in diameter, were fairly
numerous in the pockets containing dysluite, and both single crystals and
groups, with jeffersonite and dysluite, are preserved in the Canfield collection.
Bright-red dodecahedrons partly embedded in limestone were found in the
stripping of the calamine bed in the Noble mine. The best of thesea
splendid crystal measuring nearly 3 inches on the edge of the very regular
dodecahedronis in the collection at Princeton University.