David K. Joyce

Copper, Keweenaw Peninsula, Michigan, USA

The Keweenaw Peninsula of the upper peninsula of Michigan State was one of the premier producers of copper. Not on;y were astounding tonnages of copper produced but many fantastic specimens of native copper, sometimes crystallized, were produced. The mines of the Keweenaw Peninsula were mostly underground mines that tapped either humongous deposits of copper in conglomerate/basalt strata or large fissure veins. The fissure veins were the source of most of the crystallized copper specimens that you see. The conglomerate and basalt were the source of amygdaloidal copper, Copper "skulls", and sheet copper. The geology, mineralogy and history of the "Michigan Copper Country" is fascinating and you can learn more about it in the special "Michigan Copper" issues of "Rocks and Minerals", Volume 77, No.6 or The Mineralogical Record Volume 23, No. 2. Each a fantastic publication.

All prices in Canadian dollars. For payment in US$, deduct 18% or multiply by 0.82.

Click on any of the following thumbnails to view a larger image of the specimen.

Silver-CopperCopper, Keweenaw Peninsula, Michigan, USA
  • Item #28306
  • Silver-Copper
  • 1.7x1.4x0.8 cm
  • Largest Crystal Size: n/a
  • $55.00
  • Keweenaw Peninsula
    Michigan, USA
  • Here is a great example of the silver-copper nuggets that occur in the Keweenaw Peninsula. Classic!
CopperCopper, Keweenaw Peninsula, Michigan, USA
  • Item #11837
  • Copper
  • 4.1x3.2x1.7 cm
  • Largest Crystal Size: 10mm
  • $65.00
  • Phoenix Mine
  • Keweenaw Co.
    Michigan, USA
  • Nice parallel-growth group of copper crystals with some quartz attached. Looks great!
CopperCopper, Keweenaw Peninsula, Michigan, USA
  • Item #11830
  • Copper
  • 5.3x2.0x0.8 cm
  • Largest Crystal Size: 40mm
  • $60.00
  • Phoenix Mine
  • Keweenaw Co.
    Michigan, USA
  • This specimen shows one long copper crystal with a number of blockier crystals attached to one end. Great shape! Great example of copper crystals.
Silver, CopperCopper, Keweenaw Peninsula, Michigan, USA
  • Item #27116
  • Silver, Copper
  • 2.3x1.6x0.6 cm
  • Largest Crystal Size: n/a
  • $40.00
  • Keweenaw Peninsula

  • Michigan, USA
  • The Keweenaw Peninsula s famous for crystallized copper and silver specimens. Another thing it is famous for are these nuggets that are poart silver and part copper. Apparently silver can only "disolve in copper to a certain extent and then afterwards forms a discrete phase as native silver with the copper. Here is an example of that immiscibility!
CopperCopper, Keweenaw Peninsula, Michigan, USA
  • Item #20207
  • Copper
  • 18.3x6.8x3.4 cm
  • Largest Crystal Size: as above
  • $175.00
  • White Pine Mine
  • Ontonagon County
    Michigan, USA
  • An excellent aggregate of copper crystals, associated with carbonate and zeolites, from THE last native copper mine that operated in northern Michigan. I think it closed most recently in the 1990's. Here is a large specimen from that famous operation!
CopperCopper, Keweenaw Peninsula, Michigan, USA
  • Item #20306
  • Copper
  • 14.5x4.5x0.3 cm
  • Largest Crystal Size: 25mm
  • $65.00
  • Keweenaw Peninsula

  • Michigan, USA
  • although made up of 25mm or so crystals of copper, this is really one big, dendritic, branching crystal of native copper. Classic!
Copper, CalciteCopper, Keweenaw Peninsula, Michigan, USA
  • Item #20936
  • Copper, Calcite
  • 11.5x7.8x5.5 cm
  • Largest Crystal Size: as above
  • $110.00
  • Keweenaw Peninsula

  • Michigan, USA
  • A hackly mass of native copper with some openings showing whole calcite crystals, calcite crystal impressions and copper crystal faces. Such great specimens!
CopperCopper, Keweenaw Peninsula, Michigan, USA
  • Item #21421
  • Copper
  • 16.5x4.5x1.9 cm
  • Largest Crystal Size: 55mm
  • $75.00
  • Central Mine
  • Keweenaw County
    Michigan, USA
  • A huge, rough copper crystal is attached to the end of a rough, hackly mass of copper and crystals on this piece. Impressive! THAT is a big, blocky crystal!
CopperCopper, Keweenaw Peninsula, Michigan, USA
  • Item #21422
  • Copper
  • 6.4x4.4x5.4 cm
  • Largest Crystal Size: 10mm
  • $160.00
  • Central Mine
  • Keweenaw County
    Michigan, USA
  • Calcite has been carefully removed from around this copper to reveal beautiful, metallic-red, dendritic, copper crystals, in excellent branching aggregates. Superb example of this native element from the legendary Keweenaw Peninsula, Michigan.
CopperCopper, Keweenaw Peninsula, Michigan, USA
  • Item #21424
  • Copper
  • 12.5x8.0x1.4 cm
  • Largest Crystal Size: 12mm
  • $85.00
  • Central Mine
  • Keweenaw County
    Michigan, USA
  • Here is an interesting one! It is largely a plate of copper encrusted with a light greenish silicate mineral(s). Interestingly, there are several fairly sharp copper crystals poking through the silicate, here and there, on both sides. Nice crystals!
CopperCopper, Keweenaw Peninsula, Michigan, USA
  • Item #21425
  • Copper
  • 5.4x3.8x2.9 cm
  • Largest Crystal Size: 20mm
  • $260.00
  • Central Mine
  • Keweenaw County
    Michigan, USA
  • A very nice, dendritic copper specimen, reflecting the "herringbone" habit that we see in copper sometimes. Crystals are sharp and in parallel growths typical of this habit. Nice example!
Prehnite, CopperCopper, Keweenaw Peninsula, Michigan, USA
  • Item #22152
  • Prehnite, Copper
  • 5.3x4.6x4.8 cm
  • Largest Crystal Size: co-2mm,
  • $65.00
  • Iroquois Lode
  • Keweenaw County
    Michigan, USA
  • A very good looking vug of botryoidal, light green prehnite that is peppered with small copper crystals, some, fairly sharp others very distorted. Displays very well!
DatoliteCopper, Keweenaw Peninsula, Michigan, USA
  • Item #25032
  • Datolite
  • Largest piece 5.0x3.8x2.0 cm
  • Largest Crystal Size: as above
  • $75.00
  • Keweenaw Peninsula

  • Michigan, USA
  • OK, these are not copper, persay, but they do come from the most famous native copper mining area in the world. The two halves make a complete datolite nodule coloured reddish by inclusions of cuprite or possibly hematite. These nodules occur in the copper deposits and are interesting as well as beautiful!
CopperCopper, Keweenaw Peninsula, Michigan, USA
  • Item #25178
  • Copper
  • 6.1x4.4x3.5 cm
  • Largest Crystal Size: n/a
  • $40.00
  • Central Exploration Mine
  • Keweenaw Peninsula
    Minnesota, USA
  • Here is a nice specimen of native copper showing a spire of copper on one side that is trying hard to be a crystal. It is intergrown with calcite and zeolites. From the Central Mine, one of the Great old mines of the Keweenaw Peninsula.
Copper, QuartzCopper, Keweenaw Peninsula, Michigan, USA
  • Item #25949
  • Copper, Quartz
  • 2.8x2.4x2.0 cm
  • Largest Crystal Size: 2mm
  • $40.00
  • Lasalle Mine
  • Houghton Co
    Michigan, USA
  • The front of this silicified basalt host a quart crystal-lined vug that contains a branch of very sharp, slightly oxidized copper crystals. Very nice crystals!
Copper, QuartzCopper, Keweenaw Peninsula, Michigan, USA
  • Item #25988
  • Copper, Quartz
  • 3.2x2.1x1.7 cm
  • Largest Crystal Size: 2mm
  • $35.00
  • Lasalle Mine
  • Houghton County, Keweenaw Peninsula
    Michigan, USA
  • arguably, this is one, long, complex crystal made up of sharp, smaller components in parallel. Very interesting crystals!
CopperCopper, Keweenaw Peninsula, Michigan, USA
  • Item #26333
  • Copper
  • 4.9x2.5x2.2 cm
  • Largest Crystal Size: 17mm
  • $65.00
  • Centennial Mine
  • Houghton Co
    Michigan, USA
  • A cluster of elongated copper crystals from the old Centennial Mine. Sits just like this!
CopperCopper, Keweenaw Peninsula, Michigan, USA
  • Item #26334
  • Copper
  • 4.1x3.7x1.6 cm
  • Largest Crystal Size: 12mm
  • $140.00
  • Keweenaw Peninsula

  • Michigan, USA
  • Very sharp, twinned copper crystals on this specimen. The bigger crystals on the one side are excellent but the crystals embedded in the whitish and iron stained minerals are also excellent. I THINK they are twinned tetrahexahedra. Really nice specimen!
CopperCopper, Keweenaw Peninsula, Michigan, USA
  • Item #26338
  • Copper
  • 4.5x2.7x1.3 cm
  • Largest Crystal Size:
  • $85.00
  • Phoenix Mine
  • Keweenaw County
    Michigan, USA
  • A really well crystallized branching aggregate of elongated copper crystals. Looks like the crystals either formed in zeolites or were covered with zeolites later, which are still some remnants of between some of the crystals. Displays well!
CopperCopper, Keweenaw Peninsula, Michigan, USA
  • Item #26339
  • Copper
  • 12.4x5.1x3.6 cm
  • Largest Crystal Size: n/a
  • $65.00
  • White Pine Mine
  • Ontonagan County
    Michigan, USA
  • A large, thick, sheet of oxidized native copper is folded over on itself and crumpled on the ends. Really a nice, dense, interesting plate of native copper!
Copper, DatoliteCopper, Keweenaw Peninsula, Michigan, USA
  • Item #26340
  • Copper, Datolite
  • 5.8x3.0x2.5 cm
  • Largest Crystal Size: 17mm
  • $120.00
  • Keweenaw Peninsula
    Michigan, USA
  • This whole specimen is covered with copper crystals. The top crystal is an elongated grouping of crystals. The lower part of the specimen is totally composed of copper crystals that are partially encrusted with tiny, sparkling datolite crystals and epidote. Very interesting specimen from a vein deposit.
CopperCopper, Keweenaw Peninsula, Michigan, USA
  • Item #26346
  • Copper
  • 11.0x9.7x1.3 cm
  • Largest Crystal Size: n/a
  • $40.00
  • White Pine Mine
  • Ontonagan County
    Michigan, USA
  • A thick plate of native copper with some zeolite and/ore calcite attached to the back. A little on the front, too!
Copper, TenoriteCopper, Keweenaw Peninsula, Michigan, USA
  • Item #26894
  • Copper, Tenorite
  • 5.1x4.1x2.7 cm
  • Largest Crystal Size: 4mm
  • $40.00
  • Keweenaw Peninsula

  • Michigan, USA
  • Crude crystals of native copper are joined in dendritic and sheet growths in this quartz fragment breccia. Black tenorite is present in open spaces and between copper and the breccia fragments. Interesting one!
CopperCopper, Keweenaw Peninsula, Michigan, USA
  • Item #26895
  • Copper
  • 9.1x6.2x2.3 cm
  • Largest Crystal Size: n/a
  • $40.00
  • Keweenaw Peninsula

  • Michigan, USA
  • Mostly copper with a little bit of vein silicates intergrown. A copper nugget! I suspect that it was once part of a much larger, thick, sheet of native copper in a vein. Heavy!
CopperCopper, Keweenaw Peninsula, Michigan, USA
  • Item #26899
  • Copper
  • 4.2x3.4x1.4 cm
  • Largest Crystal Size: 4mm
  • $75.00
  • Keweenaw Peninsula
    Michigan, USA
  • This specimen is totally composed of twinned, dendritic copper crystals. Solid and dense! Looks great. From one of the most famous copper mining areas of the world!
CopperCopper, Keweenaw Peninsula, Michigan, USA
  • Item #26900
  • Copper
  • 3.5x1.9x1.1 cm
  • Largest Crystal Size: 9mm
  • $35.00
  • Calumet
  • Keweenaw Peninsula
    Michigan, USA
  • Flattened, dendritic mass of native copper with one particularly nice copper crystal at one end. Nice!
Copper, AlbiteCopper, Keweenaw Peninsula, Michigan, USA
  • Item #26903
  • Copper, Albite
  • 3.9x3.6x1.4 cm
  • Largest Crystal Size: 4mm
  • $75.00
  • Keweenaw Peninsula
    Michigan, USA
  • A cluster of extremely sharp, twinned copper crystals, associated with some bladed white crystals that I'm assuming are a feldspar. Really nice crystals from the famous Keweenaw Peninsula!
CopperCopper, Keweenaw Peninsula, Michigan, USA
  • Item #26907
  • Copper
  • 4.8x2.4x1.2 cm
  • Largest Crystal Size: 7mm
  • $40.00
  • Central Mine
  • Keweenaw Peninsula
    Michigan, USA
  • A group of complex crystals with sharp faces, protrude out of this fragment of basalt. Nice specimen from this famous copper mining area!
CopperCopper, Keweenaw Peninsula, Michigan, USA
  • Item #26908
  • Copper
  • 4.0x2.4x2mm cm
  • Largest Crystal Size: 13mm
  • $35.00
  • Calumet
  • Keweenaw Peninsula
    Michigan, USA
  • A flattened group of dendritic copper crystals that, presumably formed in a fracture. Beautiful!
CopperCopper, Keweenaw Peninsula, Michigan, USA
  • Item #28227
  • Copper
  • 3.9x2.0x1.8 cm
  • Largest Crystal Size: n/a
  • $65.00
  • Keweenaw Peninsula

  • Michigan, USA
  • This piece is solid native copper but not a natural form. It is a "chisel chip", a fragment resulting from the practice of chiseling down huge boulders of copper by miners. Really big boulders of native copper could not be crushed down in size but still had great value as copper. They are metal and so could not be blasted down in size, either. The COULD be chiseled down in size, though! This chisel chip is a result of that kind of work.
CopperCopper, Keweenaw Peninsula, Michigan, USA
  • Item #28233
  • Copper
  • 4.3x1.9x1.7 cm
  • Largest Crystal Size: n/a
  • $65.00
  • Keweenaw Peninsula
    Michigan, USA
  • When miners of old encountered large masses of native copper in the Michigan copper mines, they could not break them up further with explosives of machinery and so chiseled the boulders down to small, manageable bits with hammer and chisel. This is such a fragment of a copper boulder in the shape of a "chisel chip". Historical!
Silver, CopperCopper, Keweenaw Peninsula, Michigan, USA
  • Item #28309
  • Silver, Copper
  • 2.1x1.6x0.5 cm
  • Largest Crystal Size: n/a
  • $55.00
  • Keweenaw Peninsula
    Michigan, USA
  • This nugget appears to be mostly silver but I think it is about 50:50. There is a lot of copper in the lower portion and on the back. Excellent example!