The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1920-01-01
continued from last weekly
I,reous Decentralization.

,ba Pine creek district, though they
arc widely distributed. They occur as
narrow basic bikes, commonly in OF
odtacent to the larger faults, but some
have no relation to faulting. Granite
-, mennonite bikes have not been
found in the district Fine grained
aork colored dixie rocks were noted in
the Highland Surprise mine along the
Placer creek fault, in the Constitution
mine near the Pine creek fault and in
the Amy -Matchless mine and Corby
prospect adjacent to we'll defined
faults Along the belt of siderite veins
in the southern part of the Pine creek
hasin the rocks of the Ravalli group
are cut by bikes that are not related
to major faults, though they are SIM
liar to those found in the Prichard
formation in fault zones.
Photographic Features.
All the dixie rocks are classed un-
der the general term ~lamprophyre,
though when examined in thin Sec
tons they show considerable varia
ron in texture and mineral compost
tion and some are given more specific
names.
Several bikes from to 20 feet wide
were cut in a tunnel on the Palisade
group of claims. They trend from
north to N. 80 degrees w. and cut
uurple and green shales and quartz
lite of the ST Regis formation which
strike northeast and dip southeast.
The following brief Photographic de-
scriptions are largely taken from
notes by e. S. Larsen, who examined
several of the dixie rocks in thin sec
tion
One rock of porphyritic texture and
gray color from the Palisade group is
too much decomposed for accurate
Identification A little partly bleach
ed biotite, some apatite and consider
able partly decomposed plagioclase
are the only original minerals that
can be recognized. There is much
secondary carbonate, sericite, quartz
and chlorite. This rock is poorer in
dark minerals than normal lampro-
phyres.
Another dark olive-gray dixie rock
carries prominent biotite flakes. 1t
is made up of nearly equal amounts
of Divine, pale-brown biotite, and al
bite Apatite is abundant in small
rods and iron ore is present. The BIZ
lit In, tn1 nc
much as millimeters across; the al
bite is in coarse, much elongated cry
stalls, collected together in sheathlike
aggregates. The Divine is altered to
a strongly birefracting fibrous or pla- !
ty chloritic mineral similar to that
described below as occurring in the
camptonites. This rock is classed as
an Divine albite kersanite.
rock from the same locality class
ed as Divine camptonite, is very fine
grained dark olive-gray rock that
shows in the hand specimen abundant
minute prisms of hornblende. 1t is
made up of about equal amounts OF
labradite, brown hornblende augite,
altered Divine, and groundmass; /
there is some iror re and apatite The
crystals are aboLt 05 millimeter In
greatest dimension. The Divine is /
completely replaced by carbonates,
fibrous serpentine with a birefring-
ence of about DOL, chalcedonic quartz
and a chloritic mineral with strong /
birefringence. The aIgite is partly !
altered to fibrous chlorite or serpen-
tine. The groundmass is very finely |
crystalline and when fresh may have |
been partly glass.
A dixie rock in the Constitution
mine is similar to the olivine camp
tonite from, the Palisade tunnel but
1t contains more Divine and much
less hornblende. The Divine is large
ly altered to platy, strongly bire-
fracting chloritic mineral, and there is
much secondary quartz and carbonate
in the section.
Age Of Dixie Rocks.
In the Occur d'Alene district most
of the basic dixie rocks were intruded
after the period of ore deposition. The
relation of bikes to ore is not clearly
shown in the Pine creek district,
though in both the Highland Surprise
and Constitution mines the bikes oc-
cur in the ore bearing assures The
bikes are apparently nowhere replace
ed by ore, though in the Highland
Surprise mine the dixie partly in
closes the ore. This relation Is
thought to be due, however to recur-
rent movements along the fault
planes. In this mine also the ore body
has been displaced by faults, whereas
the dixie is undisturbed.
Orc Deposits-General Features.
The ore deposits of the Pine creek
district are unreasonable assure veins
and assure filings, with gradations
between the two types. The veins
that show metasomatic replacement
are best developed in shear zones
along major faults; the assure filings
are best developed along minor faults
or in zones of moderate shearing. The
deposits occur principally in the area
OF Prichard rocks, where the faulting
and distortion of the strata have been