UPDATED HOURS, EDITED 9-17-10: Due to severe
budget cuts they are only open Thurs - Sat 9 to 5 and Sun 12 to
5.
Cornwall Iron Furnace is an extraordinary example of the
furnaces that dotted the Pennsylvania countryside in the 18th and
19th centuries. Around it developed villages, artisans' shops,
stores, schools, churches, and the home of a wealthy ironmaster.
All of the raw materials necessary for the smelting process - iron
ore, limestone and wood for charcoal - were found in this self
contained iron plantation. Cornwall Iron Furnace, the only
surviving intact charcoal cold blast furnace in the Western
Hemisphere, attests to the once great iron industry that flourished
in south central Pennsylvania. Cornwall Iron Furnace remained in
operation until 1883, when newer furnace operations fueled by
anthracite coal made it obsolete. The furnace was abandoned,
leaving the building virtually untouched until it was given in 1932
to the Commonwealth of Pennsylvania by Margaret Coleman Freeman
Buckingham, Robert's great grand-daughter.
The ore mine, which continued to operate until 1973, is
located just south of the furnace property. Bethlehem Steel
acquired ownership of the mine between 1917 and 1922.
Both strip mining and underground mining were used to extract
ore from the ground.
The open pit mine began to flood in 1972, and today the open pit
is filled with water.
Magnetite ores were the main source of iron at Cornwall. Most
of the magnetite at Cornwall occurs in the massive form, called
lodestone. It has a mottled gray color and is very heavy for its
size, owing to its high magnetite content. Sometimes lodestone is
sold in science stores as "Nature's Magnet." This is not a false
claim; lodestone will attract iron filings and other small
lodestone pieces. At Cornwall, metamorphism is responsible for the
wide variety of minerals that occur there. According to the
Pennsylvania Geologic Survey, about 90 different minerals have been
found at Cornwall.
Limestone is one of the two major rock masses that formed the
Cornwall site, and where there's limestone, dolomite is present as
well. Most dolomite is mixed into the rocks at Cornwall, but some
can be found in crystal form.
The other major constituent of the Cornwall area is a dark-colored
igneous rock called diabase, One of the most widely known minerals,
calcite, is present at the Cornwall mine. As stated above, the two
major rock bodies responsible for the ore at Cornwall are diabase
and limestone. Diabase is formed when a mass of magma (underground
lava) undergoes a slow cooling and crystallization process at
depth. The resulting rock body is called a pluton. In the Triassic
period, large bodies of magma spread up and into pre-existing
Cambro-Ordovician limestone beds all over eastern Pennsylvania. The
high temperature of the magma altered some of the sedimentary rocks
with which it came in contact. Over a large area, this action is
called contact regional metamorphism. The magma then cooled into
the diabase we see today.
Please enter the Visitors Center and proceed to the exhibit
room directly to your left. From the displays you will find the
information necessary to complete the following requirements and
e-mail them to me. Do not include this information in your log
below.
1. How many tons of iron ore was extracted by the miners here
over 230 years in operation?
2. What is the name of the "stone" on display just after you
pass the cannonballs and cannon, c.1776?
3. How do you think it got that name?
4. List 4 of the other minerals found at the Cornwall Ore
Banks?
5. What is gangue? When the ore is smelted, what does gangue
become?
6. What is the "chemical sponge"?
7. After leaving the Visitor's Center, proceed up Boyd Street to
these coordinates:
N40' 16.104 W076' 24.264
Near here you can view the abandoned mine from a safe
distance. Across from the historic marker, please take a photo with
your GPS and the filled in mine in the background. Send me an
email,estimating the width of the lake (filled-in mine) at the
second coords, or providing a brief description of what evidence
(if any) of the mine can be seen here. Behind you is "The Big Hill"
where you can still find examples of the various geology of the
mine era. But do not venture past the "posted area"
The Cornwall Furnace area is not just part of Pennsylvania's
Historical Trail but rather it is an interesting locale rich in
geologic history.