Stamp sand is a coarse

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class ...

left over from the processing of ore in a

stamp mill A stamp mill (or stamp battery or stamping mill) is a type of mill machine that crushes material by pounding rather than grinding, either for further processing or for extraction of metallic ores. Breaking material down is a type of unit operati ...

. In the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

, the most well-known deposits of stamp sand are in the Copper Country of northern

Michigan Michigan () is a state in the Great Lakes region of the upper Midwestern United States. With a population of nearly 10.12 million and an area of nearly , Michigan is the 10th-largest state by population, the 11th-largest by area, and t ...

, where it is black or dark gray, and may contain hazardous concentrations of trace metals. In the 19th and early 20th centuries, many metal mines used stamp mills to process ore-bearing rock. The rock was brought to a stamp mill to be crushed. After crushing the material was mechanically separated to extract metals, or chemically treated by acids if the metal could be leached out. The size of the crushed material depended on the nature of the ore found in each mining district.

Copper Country of Michigan

In the Copper Country region of the

Upper Peninsula of Michigan The Upper Peninsula of Michigan – also known as Upper Michigan or colloquially the U.P. – is the northern and more elevated of the two major landmasses that make up the U.S. state of Michigan; it is separated from the Lower Peninsula by ...

, the rock was reduced to fragments because further crushing would not result in enough additional copper recovery to be economical. The sand was then usually disposed near the mill. As mills often relied on

steam power A steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a cylinder. This pushing force can be tra ...

to operate and water for some of the processing methods, they were built on the shore of lakes and rivers. The stamp sand was thus dumped into the water, sometimes growing deep enough to create entirely new land. Stamp sand discarded into the water was sometimes reclaimed with dredges to be re-stamped when more efficient stamping technology was developed (for example, Quincy Dredge Number Two). Stamp sand may be hazardous to human health, since it contains trace amounts of harmful heavy metals (such as

arsenic Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, b ...

). For this reason, land created from stamp sand may be poisonous to plant life, and can pollute nearby water as well. For example, aquatic life in the

Keweenaw Waterway The Keweenaw Waterway is a partly natural, partly artificial waterway which cuts across the Keweenaw Peninsula of Michigan; it separates Copper Island from the mainland. Parts of the waterway are variously known as the Keweenaw Waterway, Portage ...

, near the

Keweenaw The Keweenaw Peninsula ( , sometimes locally ) is the northernmost part of Michigan's Upper Peninsula. It projects into Lake Superior and was the site of the first copper boom in the United States, leading to its moniker of "Copper Country." As ...

copper mines of Michigan, has declined significantly near stamp sand deposits, while the waterway is reasonably healthy in other areas. Several stamp sand dumps have been designated as

Superfund Superfund is a United States federal environmental remediation program established by the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA). The program is administered by the Environmental Protection Agency ...

sites to remove or contain the sands. Some stamp sand land has been covered with clean fill dirt and used for housing developments. The coarseness of the sand has led to its use in place of (or in combination with) road salt in some areas, such as the Copper Country of Michigan. Typically, only stamp sand which has not been chemically processed is used, due to environmental concerns. In addition, some companies have developed methods to reprocess stamp sands to reclaim their small mineral content.

References

External links

Stamp sand research
in the Copper Country {{Extractive metallurgy Upper Peninsula of Michigan Metallurgical processes Stamp mills

Copper Country of Michigan

See also

References

External links