Connection to the Earth Science Curriculum
Essential Lessons:
The Earth has always been pretty much the way it
is now.
6th grade learning outcomes
E. SE. 06.12- Explain how waves, wind, water, and glacier movement, shape and reshape the land surface of the Earth by eroding rock in some areas and depositing sediments in other areas.
Ore-
a material that can be economically mined. If you remove
the material
from the ground you can
make a profit.
Mining-
removing the ore from the non-ore rock
Stamp
mill- a machine for stamping ore
Waste rock (poor rock)- all of the material that is left over after you remove the metal from the ore. It has no economic value at this time and so is dumped on a waste pile away from the ore bearing rock.
Fissures vein- a crack in the earth’s surface filled with mineral matter
Amygdaloidal- top layer of a lava flow generally rich in minerals
Conglomerate- rocks of stone fragments cemented together by a mineral or other substance
Delaware
Copper Mine
EarthCache
Materials needed
for your visit-
GPS and local rock/
mineral
guide for Michigan
Coordinates: 47° 25.410'N 88° 6.121'W
A Precambrian Midcontinent rift formed around 1.1 billion years ago. Over the next 100 million years layers of volcanic and sedimentary rocks were deposited into the rift valley. Then hot water moved through the rocks filling the open pore spaces with native copper and other minerals. (Hydrothermal mineralization) The copper is commonly found in the permeable layers of conglomerate between the sand and pebbles.
The
Keweenaw
Peninsula has two types of copper deposits- Lode deposits and fissure
deposits.
The lode deposits comprise of conglomerate lodes (rocks held together
by
copper), and amygdaloidal lodes (almond-shaped deposits in the top
layer of
lava flows)
The fissure deposits are
veins along fractures
that parallel or cross the beds.
Originally
the Delaware mine started by mining a fissure vein.
The ground was poor but
there was enough copper to continue mining that site. Mining fissures
was
difficult for the miners to remove the large pieces of copper. Later
miners
started to mine conglomerate loads because the copper was easier to
remove and
more consistently found than in the fissure copper lodes. The
conglomerate
loads could be mined more efficiently with the ore blasted out, taken
to the
surface and then railroaded to stamp mills.
Even
though the
conglomerates were rich in copper only about 2% of the ore/ rock hauled
to the
surface was copper. The remaining rock was called poor rock and set in
piles
near the mine or hauled away and put to other uses. Another waste
product of
mining was stamp sand. Stamp sand is still a problem plaguing the
Keweenaw
Peninsula.
Figure 1-Tailing pile at the Delaware mine. Waste rock pile
at the Delaware mine.
Source: ©
Paul T. Brandes Photo
ID: 248417
Figure 2 – Bedrock Geology. This map illustrates where
copper conglomerates are located.
http://www.dnr.state.mi.us/spacialdatalibrary
Describe the types of rock found in the waste rock pile, include color, texture and shape.
What are some possible uses for this type of rock?
Access Information-
Owner of site- Tom & Lani Poynter – private
National Park Preserving natural history
References and citations
Brandes, P. (2008) Geology of the Keweenaw Peninsula, Michigan.
Retrieved July 28th ,2011 from http://www.mindat.org/article.php/255/GeologyoftheKeweenawPeninsula