CALEDONIA MINE
Mass City, Ontonagon Co., MI
August
7, 2003
Caledonia
Mine Portal
An
ore car from the Caledonia Mine
I
had visited the Caledonia two years ago, but decided to give it another try
this year. This mine is being operated for specimens and collecting. They
offered underground collecting as well as surface, but I opted for the surface
collecting.
This
mine is quite a ways south of where we were camped. It’s just past the Knowlton
Mine, which I visited on Tuesday. The exact location is Lat. 46 deg. 45.064’,
Lon. –89 deg. 07.215’. Although we had to park on the road and walk down into
the dump, after the trip was over collectors were allowed to bring their
vehicles down into the dump to haul out what they had collected.
There’s
a lot of calcite here, and most of the crystallized copper is under it. You
don’t know what you got ubtil you get it home and leach out the calcite with
acid. Some people in the area recommend sulfamic acid, but I haven’t had much
luck with it. I prefer to use muriatic (hydrochloric) acid diluted about 1:1
with water. As long as you don’t leave the specimens in the acid too long there
isn’t much danger of etching the copper. I’ve found that about 2 hours works
well. Of course, you have to thoroughly rinse with water to remove all acid,
and possibly neutralize with an ammonia rinse before drying the specimens.
In
addition to the copper, there’s a lot of epidote, pumpellyite, quartz and
saponite. The microcline (var. adularia) is the best I’ve seen in the copper
country. In addition to the opaque orange-red crystals that are seen everywhere
in the copper country, there are also delicate pink translucent crystals.
Silver and datolite are also reported from here, but I didn’t find any.
On to the next field trip: the
LaSalle Mine