Mines and Minerals

Mining for Metals Exploration

Precious metals have been discovered in a new location. Due to government regulations, your mining company is only able to buy the rights to one plot of land. Investigate samples from two different sites and determine which site would be most profitable for your company to mine.

Learn More

Early Mining Activity In New Jersey

A pluton is a large body of intrusive igneous rock. Magma from a nearby volcano travels horizontally beneath the surface forcing its way through surrounding rock. The high heat and pressure of the magma flow causes minerals to form as the magma cools.

The now abandoned North Arlington, New Jersey, copper mine is a good example of this type of mineral formation. Sandstone (a sedimentary rock) collected near the mine often contains layers of metamorphic rock formed by the pressure and heat of intrusive magma. Often an ordinary chunk of meadowlands sandstone contains amethyst crystals and thin lines of copper. The magma came from volcanic activity in the Newark basin 200,000,000 million years ago when the break up of Pangaea created the Watchung Mountains that are regions of plutonic uplift.

During New Jersey's colonial period, bog iron was mined by open pit methods. Iron from New Jersey was used by colonists during the Revolution to make ammunition and cannons. Although the large chain that spanned the Hudson River during the Revolution was forged in Orange County, New York, it is possible that bog iron from New Jersey contributed to its production. The Great Chain was used to prevent British warships from using the Hudson River. West Point was a strategic location for blocking the advancement of the British navy.

Bog iron forms when iron rich sediments are carried away from mountains through the processes of weathering and erosion. The main type of rock in New Jersey bog iron is magnetite. Because bog iron is formed by sedimentation, it is often mixed with other minerals. The remains of an early 1800's iron furnace can be seen near West Milford, New Jersey. Trees were cut down to make charcoal needed to generate high heat in the furnace. Iron was then purified through a forging process. The furnace was forced to close when the nearby wood supply was exhausted. The Clinton furnace is on the national registry of historic places.

Zinc and iron were once mined at Sterling Hill in Ogdensburg, New Jersey. Like the copper mine of North Arlington, Sterling Hill was an underground mine. The mine closed in 1986 and reopened in 1989 as a mining museum. Franklinite, fluorescent mineral, is found nearby at the Franklin Mine. Located in the Ridge and Valley region of New Jersey, the geology of this area reflects tectonic activity of the Precambrian and erosion during the late Mesozoic and early Tertiary eras. Glaciers of the Pleistocene created surface deposits of mineral rich boulders that were profitable for mining.