Float Copper

Float Copper is also called Drift Copper or “Butchite” What do these names mean and where does this copper come from? We know copper is heavy …so how can it “Float” or “Drift”…and what does it Float or Drift on?

The term “Drift” refers to glacial drift, which is any sediment deposited as a direct or indirect result of glaciation. Copper nuggets that are carried by glaciers and the runoff melting water streams or rivers are “Drift Copper”.

The term “Float” is a geological term and refers to any material that has been carried by erosion away from the location where it was originally formed. A piece of rock that slides down a hill is now “Float”. (Also referred to as a “Floater”)

In this case a glacial movement carried a nugget many miles and then the nugget slides off the glacier as it melts. That nugget is now correctly referred to as both “Drift” and “Float”, whose original location where it was formed is "Up Glacier" somewhere.

The term “Butchite” appears to be a local term that is given to a piece of Float Copper after it has been polished and sealed to prevent further corrosion. There is no official record of the term “Butchite” in either Mindat or Mineralogy Database sites, or any dictionary or encyclopedia we have found as of yet…(we will appreciate any update or more precise information our readers may have)... It may be a misnomer... taken from the term “Buchite” which may be defined as a vitreous metamorphic rock produced by the contact action of basalt or by friction metamorphism.

10/14/2019...New information on the term "Butchite".... Received the following e-mail explaining where the term came from today...

“Good morning, I came across your web page as I was looking for some other information this morning on the web.I saw your description of the selectively polished float copper pieces a.k.a. "Butchites", A little history- Years ago Ken had a guy by the name of Butch working for him at the production shop that was really good at polishing float copper pieces. Over time the term "Butchite" evolved to refer to the pieces he did. Butch no longer works for us, but his legacy lives on.Great web site as well!! Thank you, Ryan Keweenaw Gem & Gift, Inc.” (Ken refers to Ken Flood, Geologist at Keweenaw Gem & Gift)

Float copper is found in all states that have received glacial drift from the Lake Superior region. It is easily recognized by its bright green to black alteration crust consisting of malachite, cuprites and other minerals, high density, malleability and brilliant copper color on a fresh surface. Most of the Float Copper is found throughout the Copper Country of Michigan and many nearby states. Glacial movements thousands of years ago altered the geologic deposits of the native copper by tearing and scouring the land. Copper, along with other rocks, gravel, and sand were constantly tumbled and deposited over large areas of the Upper Midwestern United States. Exposure to the soils, water, and air has oxidized the copper surface a bright green. These specimens with the natural oxidation color provide an excellent contrast to the polished copper surface on these specimens.

Michigan's Keweenaw Peninsula is the most important locality in the world for pure native copper. Mining began in 1845 and continued until 1968 and over 5 million tons of refined copper were recovered from Michigan's copper mines. In the early 1900's it led the world in copper production and "Lake Copper" (as copper from this area came to be called) became the purity standard to which other refined copper was compared.

Many years before the mining operations of the past century began in the Keweenaw, prehistoric people dug copper from the mineral rich veins. Dig sites have been found as evidence of earlier mining.