You have been shuffled about the under ground for over 700 million years. You have been shifted, exposed to melting-point temperatures, smashed, carried around by water, deposited, dug up, burned, and deposited again. Your final resting-place is in the Shenandoah Valley, somewhere within the lines of Shenandoah, Rockingham, or Augusta counties. Why is it that after all of this time and devoted work, you end up stuck in the mud beside a river? The reason is because you are a fragment of iron, extracted from iron ore, and involved in the composition and production of pig iron in the early 19^th century. Some questions arise concerning your geological origins, as a piece of iron ore. For example, What is iron ore composed of? Where does it form? What happens to it when it is placed in the fiery blast furnace? These are questions that are still being researched today by geologists.

"Iron ore is a term used to denote iron-rich minerals that are commercially viable for exploitation, i.e., of sufficiently high iron content, accessible, upgradable and in the right geographic location." (Click here for more information about iron ore) The iron ore used for pig iron was mined from the surface of the earth. Iron as an element exists in many of the rocks in the Blue Ridge and Allegheny Mountains, like granite, shales, and limestone. The quantities of iron in these rocks are too small to be useful, however. Two types of iron ore were mined from the Valley of Virginia in the Nineteenth Century for the manufacturing of pig iron. These two ores are Hematite (Fe₂O₃) and Geothite (FeO (OH)). This iron existed in quantitative deposits.

Hematite and Geothite formed in concentrated deposits due to many complicated chemical and geological processes. These processes started in a time period beginning approximately 700 million years ago. The surface of the eastern United States consisted of a definite pattern of rock that lied underneath a prehistoric sea, underneath which would have been a layer of limestone, followed by a layer of sandstone, and then a layer of much harder minerals like granite and quartz. This can be seen in Diagram 1.

Due to plate tectonics and continental shifting, the African continent collided with North America over the next 550 million years. Very slowly, the land began to shift inward, causing the layers underneath to rise. The top layers described in Diagram 1 were upset, and eventually the bottom ones were pushed to the surface. This left older rock closer to the surface, and actually on top of the younger rock formations. This is illustrated in diagram 2.

As a result, diagram 2 is a cut-away, side view of the present Blue Ridge Mountains. The mountain formation today is due not only to ancient continental collision, but also weathering. Rocks with harder composition form the summit or ridgeline, and the sandstone forms what could be called miniature foothills. They formed because of erosion.

 The location of the harder rocks, at the top, is the first necessity in the formation of concentrated iron ore deposits. The elevation allows the iron to start at the top and move down hill. Iron, however, is only mobile in its ionic form (Fe²⁺). Over time, acids, such as carbonic acid, form with the rain and erode the minerals. This converts the existing iron to its ionic form in solution. The ionic solution allows the iron to move down hill, another necessity. When the acidic iron solution reaches the limestone at the foot of the hill, it enters a basic environment (basic- having a pH greater than seven). This causes the iron ions to oxidize and precipitate. In other words, all of the iron becomes solid again, and it falls in the same place. Hence, a concentrated iron ore deposit. Consequently, these deposits can be found all along the western side of the Blue Ridge Mountains. There aren’t any of these deposits to the east because of the lack of limestone. There are also deposits in the Allegheny's that formed from this same process. Due to the difficulty and labor involved in transporting large quantities of ore great distances, iron masters placed their furnaces close to the ore deposits. Here is a map of the iron furnaces in Virginia. Notice that they all fall along the edges of the mountains and the "Great Valley."

 After these ores were discovered, slaves began to mine them for use in the blast furnace. There is no possible way to get pure iron ore from the ground; it is collected with small amounts of rock and mud. This mixture was thrown into the furnace, along with charcoal and limestone and heated to temperatures ranging from 400^o to 1600^o. When the ore melted down, the pure iron flowed to the bottom of the furnace and was extracted through ducts. From the ducts it flowed through a trough known as a "sow," and into a bed of sand. The sand was shaped in a long half-cylinder and served as a mold for the iron. The resulting nickname for the hardened iron became, "pig." Hence the term pig iron." The leftover material was also melted down, but it formed a molten layer in the furnace above the iron. This is called slag. Slag was also removed as a liquid, then discarded after it cooled. Slag remnants can still be found today at historic sites of these furnaces. Not all of the iron could be removed from the slag and it was sometimes thrown back into the furnace to be re-melted.

 In conclusion, the geological origin of iron ore relates directly to the beginning of the earth. Millions and billions of iron particles from all over the world got tossed around, smashed, ground up, absorbed in acid, transported in water, suffocated in mud, and left in the hands of slaves to begin one of the greatest technological advances in history: the production of pig iron. The Shenandoah Valley is unique due to the tectonic shifting of the earth and chemical processes that have taken place over time. This coincidentally produced iron ore. Not just iron ore by itself, but concentrated deposits of it. Studying the reasons why iron ore is present in these locations can help researchers and iron producers to find deposits today. The blast furnaces today require much less labor, and are more efficient. Therefor iron is produced at a faster rate today than 100-200 years ago. The Shenendoah Valley was eventually exhausted of its profitable iron ore for the technology level of the 19^th century. Will this happen to the present technology? Maybe account should be taken that someday naturally occurring iron ores, and possibly all natural resources will be gone.