November 3, 2012 (Saturday):
Cornwall Tailings, Cornwall, PA (10:00 AM - 3:00 PM) Directions will
be e-mailed to those who signed up.
We will be visiting a
different tailings site than the golf course's this time. Tom Pankratz
will update us just before the trip.
minerals at Cornwall are associated with two major rock types:
diabase and limestone.
The Triassic diabase is an igneous rock of dark green to black
color containing feldspars and pyroxenes, with minor amounts of biotite,
ilemenite and hornblende.
The diabase formed by crystallization of these minerals from a molten
rock that cut upward through surrounding cambrian and Ordovician
limestone. This diabase, as
it cooled and solidified, recrystallized some of the limestone into
marble. Several minerals,
such as diopside, actinolite, epidote, and garnet, also formed in the
limestone partly as a result of the heat from the diabase and partly as
a result of the addition of some chemical elements from the final
crystallization of the diabase.
Later, additional solutions spread outward along the top of the
diabase into the limestone.
The magnetite, hematite, pyrite, chalcopyrite, actinolite and chlorite
formed at this stage.
Sometimes they replaced the limestone, and sometimes they
replaced the previously formed diopside and actinolite.
The zeolites, sulfated, hydroxides, and copper carbonates
crystallized last, filling open fractures and cavities.
The consequence of this series of geologic events has resulted in
certain minerals occurring together.
Three such examples are the associations 1)
magnetite-chalcopyrite-actionlite, 2) zeolites-chlorite-magnetite,
and 3) garnet-tremolite-calcite-serpentine.
The age of the ore deposit is approximately 190 mya, which is
within the Triassic period.
Geologic Time Scale
MinDat list 75 minerals that have been found at this site.
mines at Cornwall have been closed for some time, and are now imploded
and/or flooded. However
extensive tailing piles remain and we have been granted permission to
collect at one. I don’t
think we, or anyone else, has collected at this particular site.
It is quite large being perhaps 100 X 300 yds roughly a
triangular shape. The rocks
appear to be mostly diabase; little limestone was evident.
Virtually all of the rocks are dinner plate sized and smaller.
Just to be clear, this site in NOT located on Haines & Kibblehouse
quarries property. We will NOT be visiting their site on this fieldtrip.
We have exclusive, express one-time permission from the landowners of
the site that we will be collecting from this fieldtrip.
are 2 other large tailings sites in the Cornwall area and I’m working on
getting permission to visit them also.
One is diabase and the other limestone
It is about a ¼ mile walk from a parking area to the tailings
piles. For the most part
it’s a very easy walk. This
is not necessarily a strenuous collecting trip, depending on how much
You will need to bring leather boots (I don’t think you need
steel-toed), gloves and goggles (hard hat optional)
Bring rock hammers, chisels and small sledges (2-5 lb range),
wrapping material and flats (I don’t think a sledge is necessary).
Also bring lunch, snacks and drinks if you want.
The site is in Cornwall, Pa which is a 1 ½ - 2 hr. (60 mi.) drive from
Delaware. I will
provide explicit directions to participating club members.
This Field Collecting Trip is for Delaware Mineralogical
[Tom Pankratz, Vice-President of Fieldtrips]
Previous dates for this Fieldtrip:
May 12, 2012,
Saturday: Cornwall Tailings, Cornwall, PA (10AM-3PM)
May 17, 2008, Saturday:
Haines & Kibblehouse Cornwall Materials Quarry, Cornwall, Lebanon County, PA: (8AM-12PM) (Tentative)
This quarry produces magnetite, garnet, hematite, chrysocolla, pyrite,
chalcopyrite and many other minerals. Please sign up by May 15th
if you would like to attend!
October 22, 2005, Saturday: Cornwall Mine,
DMS invites its members to visit the historic Cornwall Iron
Furnace in Lebanon County. Combine a little bit of
history with some mineral collecting! Junior members are
invited to attend! The minerals that can commonly be found
here include: azurite and malachite coatings, calcite,
magnetite and pyrite.
for a list and
photographs of the minerals that have been found at this mine.
For more information about the historic Cornwall Iron Furnace
and a location map, please see the following