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New Mexico Mineral Symposium — Abstracts

A copper bowl with a silver lining

Tom Rosemeyer

Magdalena, NM,

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Silver on copper. 7.2 cm, Southwest orebody, White Pine mine, Ontonagon County, MI. Peter Rodewald specimen and photo.
Silver specimen, 9 cm, Quincy mine, Hancock, Houghton County, MI.
Tom Rosemeyer specimen, Terry Huizing photo.

This year’s talk at the symposium will dwell on the silver specimens from the Michigan Copper Country. In the title the copper bowl refers to the largest native copper deposit in the world ever mined, and the silver lining refers to the silver specimens found within that now grace mineral collections worldwide.

The first silver recovered was probably by Paleo- Indians who fashioned tools and weapons from “float copper.” Some of the “float copper” contained globs of native silver and the term applied to this combination of silver/copper was “halfbreeds.” This term is still used for silver/copper specimens from the region.

The first mining of native copper from the Keweenaw was from fissure veins cutting across the Portage Lake Volcanics.

Many beautiful specimens were recovered from the mines when miners soon learned the value of the specimens. The most outstanding specimens were from the Cliff mine and Central mine. The Kearsarge copper-bearing amygdaloidal lode produced the most beautiful and best crystallized silver specimens and are now highly sought after. A late comer for crystallized silver specimens was the White Pine mine in Ontonagon Country which mined a sediment hosted chalcocite deposit.

At present silver specimens are still being recovered by metal detecting and found as float, in mine dumps and near cabin foundations where miners had stashed specimens and didn’t retrieve them. If you visit the Copper Country a must is a visit to the A.E. Seaman Mineral Museum on the Michigan Tech campus where many beautiful specimens of silver/copper are on display.


silver, White Pine mine, Cliff mine, copper

pp. 8

42nd New Mexico Mineral Symposium
November 11-13, 2022, Socorro, NM
Print ISSN: 2836-7294
Online ISSN: 2836-7308