Know Your Rocks

Silver & Copper Halfbreeds

One reason Copper from Michigan’s Copper Country was so coveted was due to excellent electrical conductivity. Native Copper came from the ground almost pure Copper, but might be “polluted” by tiny amounts of Silver. This natural occurrence of silver, it made Michigan Copper the best conductor available. Technology was helping needed this super-conductive copper for new power lines.

Several mines in the Copper district were considered Silver and Copper Mines. Copper was, of course, king, and the mine owners were only marginally interested in silver. It was not uncommon for the miners to take any silver home with them, and in general, the Copper mine owners, looked the other way.

Often Silver and Copper were mixed, but separated in the Native Minerals. Not many things are as striking as a nugget of copper with areas of silver in them. These nuggets were found in the Keweenaw as “float”, carried and flattened by the glaciers, and most often plucked from the conveyors of the mills, after the calcite and other minerals were cleaned by the hammer mills.

A few of these nuggets of copper containing silver are still available. These nuggets have always been referred to as “Halfbreeds”, part copper and part silver. Rockhounds are excited to find one of these unusual treasures.

Halfbreeds can make beautiful jewelry as well as wonderful additions to anyone’s rock & mineral collection.