MINERALOGY
457
Genth describes aragonite from Friedensville
as follows :
“A highly
interest,ing
zineiferous
variety
of aragonite,
in crystals
of
three-fourths
to one in’ch in length,
forming
radiating
groups of a white
and yellowish-white
color,
has been observed
at the Friedensville
Zinc
Mines, by Prof.
W. Theo. Roepper,
who kindly
furnished
me with
his
analysis.
“It contains
‘Carbonate
of lime . . . . . . . . . . . . . . . . . . . . . 94.20
Carb0nat.e of zinc . . . . . . . . . . . . . . . . . . . . .
4.73
Insoluble
.............................
0.53
99.46
“Most
(Genth,
of the aragonite
1875, pp. 162-163.)
from
Friedensville
Dolomite
contains
carbonate
of zinc.”
(CaMgCOe)
Dolomitic limestones are widespread throughout the limestone belts
of the county. In small c,avities in these limestones it is not unusual
to find small saddle-shaped crystals of dolomite. Some fine specimens
are to be found in the rock waste beside the open pit of the Ueberroth
zinc mine, Friedensville.
The magnesium carbonate in the magnesian limestones ranges up
to approximately 45 percent. With the exception of the Jacksonburg
limestones used in manufacture of portland cement and occasional
beds within the Beekmantown formation, it is unusual for any limestone from Lehigh County to show less than 5 percent MgCO,, thus
indicating the widespread occurrence of dolomite.
Azorite
(Cu~(OH)~(CO~)~)
and
M&white
(Cuz(OH)zCO~)
iizurite
and malachite are included in the minerals of Lehigh
County although no actual occurrence is known to the writer.
On the
north slope of Flint Hill, a part of which comprises the extreme southeastern corner of the county, some prospecting for copper ore was
carried on about 30 years ago. Malachite coatings of limestone pebbles in the Triassic limestone conglomerate were fairly abundant.
Some of the limestone pebbles had been removed by solution, leaving
cavities whose sides were covered by a thin film of malachite.
Inasmuch as the same rock f,ormation extends into Lehigh County it is
probable that careful search may show that malachite occurs in this
county as well. Azurite commonly is associated with m,alachite so
that it may also be present.
Lanthanite
(Laa,Cez)
(COa)s.f!HzO
Probably the rarest mineral thus far reported in the county is
lanthanite.
Only a single specimen has come to light even thmough
extended search has been made for more material.
In 1853 Dr. W. W. Dickenson, the superintendent of the then active
zinc mine at Friedensville,
observed a pinkish piece of rock thrown
out of an exploratory shaft. It was about the size of a man’s fist and
founld about 6 feet from the surface embedded in “ochery soil,” evidently largely residual clay resultin, 0 from the solution of the limestones. It was close to a calamine vein and was first believed to have
originated from either the dolomitie limestones or the zinc ores.
Further investigations seemed to indicate that it was probably derived