360 V. DOLMAGE.

edly of primary origin. A small bleb of galena is shown in
Plate XXIV., A.

Zinc blende was found in only one specimen where it appeared
as medium-sized grains, which contain numerous small specks of
chalcopyrite, and in one case bornite.

Magnetite and hematite are, as usual, abundant. In some por-
tions of the mineralized bed magnetite forms large veins, asso-
ciated with quartz and epidote, or occurs in well-developed octa-
hedrons on the walls of open cavities. Hematite is pentifully as-
sociated with the magnetite and has extensively replaced it along
fine ramifying veinlets and also along regular crystallographic
lines, in the latter case forming a reticulate structure. Veinlets
often follow the line between the magnetite and the gangue. The
replacement of the magnetite is shown in Plate XXIV., B. Hem-
atite is more plentiful in the ore than in the wall rock and greatly
exceeds the amount of magnetite. It is replaced by hematite and
sulphides; grains of it are frequently seen coated with a shell of
bornite, or chalcocite, or both. The hematite on the other hand
replaces the sulphides and very faithfully follows the contacts
between the sulphides and gangue.

Calcite is later than the hematite and other minerals, and oc-
cupies small veins irregularly cutting the ore. It is, also,
found in veinlets following the contact of the hematite and epi-
dote. A vein of this calcite is shown in Plate XXIII, A, as a
black line between the gangue and the sulphides.

Paragenesis.—As well as can be made out from the structures
seen in polished sections the order of deposition of the minerals
is as follows:

[ Epidote,
|osaria, and actinolite,

Quartz,
Hematite.

Zinc blende,
Chalcopyrite,
‘TI.4 Bornite,
Chalcocite,
Galena.