Preface
Introduction
Why Pennsylvania Fluorite?
A Rare Treat:Kerry Matt Photos
Chemistry & Science
Pennsylvania Fluorite Geology
Mineral Associations
Geologic Age
Predominant Fluorite Colors
Two Museums of Note
Uses
Links
Members' Gallery
Article Contributors
Photo & Graphics Credits
Suggested Reading
Invitation to Members
Past Minerals of the Month
Pennsylvania State
Flag
Image courtesy of Marchex, Inc.
©2007, World Flag Database
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| What's in our own backyard?!...
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...why Pennsylvania Fluorite, of course!
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(Top, left): Purple Fluorite & Pink Dolomite, Binkley-Ober Quarry, E. Petersburg, PA
Photo by Ken Casey ©2007(Top,
right): Purple & Green Fluorite, New Paris, PA
Photo by Ken Casey ©2006 |
Preface
This
month, we explore in our own backyard: Pennsylvania Fluorite.
Well, we've been around the world on our quest for noble Fluorite. Yes, it's time to
come
home. So, let's find out what's in our own backyard! Everyone, everywhere,
please join us! Let's go!
Introduction
Welcome back to
our newest installment of Mineral-of-the-Month!
Now in colder
February, our journey will take us through the southeastern and central parts
of the Keystone State: Pennsylvania!
You might be saying, 'Ken, are we visiting
Fluorite yet again?!' I would answer, 'Yes, of course.
Except this time, we are going in depth to local Pennsylvania locales.' So, if your
game to follow
the theme of our club's March 3-4,
2007 Show, please do trek with us. Enjoy!
Why, look at all of the locales we
might procure some from! One could spend an entire season
or two of collecting to free these beauties from their host quarries. Check out the
map below:
 Map of Documented Fluorite Locales in Pennsylvania from many sources
(Ken Casey)
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Within a
2,000 square mile area alone for searching, an avid rockhound could devote an entire
career to discovering or writing about this month's favored mineral. As you could
tell by now, this
author is keen on Fluorite, especially those found in our backyard.
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As a rare treat, I'd like to share with two photos of some extremely nice specimens of
purple fluorite from the Burkholder Quarry. The mine section from which these
phenomenal rocks came has already been mined out. These masterful photos were taken
and shared by our new friend, Kerry Matt. Kerry is a member of
the Central Pennsylvania Rock & Mineral Club
of Harrisburg, PA. |
| Kerry Matt (left) shows his new
book at our show |
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Photo by Ken Casey |
Kerry has written a book on Pennsylvania Minerals, called
Pennsylvania's Rainbow Under Ground.
Well it's here, along with two other related works! Check it out:
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Kerry Matt’s Books
Books are ready and available. It is
possible to acquire them via
Kerry’s e-mail.
You’ll have to ask him about shipping costs to your area.
Pennsylvania's Rainbow Under Ground
$80.00 each. It’s chock full of color macro specimen photos; comes
with CD [includes 200+ additional pages, about 440 pages in all!]
Pennsylvania Paleozoic Playground
(fossils) $40.00 each. This book covers the major fossils found in
PA in a more general or basic level. (limited Self printed spiral
bound with lamin-a cover) or on CD at $16.00 each.
The Lower Cambrian Explosion of life in my
back yard (fossils) $30.00 each. This one focuses entirely
on the local material here in the Lancaster area. It is a detailed
report on fossils pre-dating the famous Burgess, all of which I
document on personal level of experience from local excavations.
(self-printed spiral bound with lamin-a cover) at $30.00 each
(limited print). And CDs at $16.00 each.
He also has a few Pennsylvania Paleozoic
Playground that are un-edited at -$10.00 discount.
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Purple Fluorite Cubes on Quartz
Burkholder Quarry, |
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Lighter Purple Fluorite
crystals
Burkholder Quarry, |
| Photos by and
courtesy of Kerry Matt ©2007 |
Chemistry &
Science
We know the basic chemistry of Fluorite.
We know it's chemical name and formula: Calcium
Fluoride, CaF2. From our basic chemistry, we discern that Calcium (Ca) is
a cation, and Fluorine (F)
is the anion. In the hydrothermal solution process, Calcite (CaCO3) gives
up its carbonate anion, or
its CO3, in exchange with the highly reactive Fluorine (F) anion, hence, CaF2.
Other elements may
play a role, but we'll keep it simple for now.
Simplified Chemical equation for the formation of
Fluorite (Ken Casey)
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In Pennsylvania,
the process is no different. Though some propose artesian meteoric groundwater
as the mechanism, and others proffer a hydrothermal formation process, the general ionic
exchange is
relatively the same. Let's explore some of the mysteries of Pennsylvania Fluorite!
In underlying
ancient limestone strata, vugs and cracks hide pristine cubes of gemmy purple
fluorite! If we could dig these natural wonders from the surface by hand, we would
have hit the
motherload of all PA fluorites. However, in most all cases, we can only obtain rare,
undamaged
specimens by support of the local mining process: open pit quarries. Thanks to them,
their benches
and spoil piles paint a geological view over millions of years in their freshly-cut
cross-sections.
Pre-fractured boulders are now open to our hunting gaze and accessible with our collecting
tools.
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Two examples of
well-formed, gemmy purple Fluorite cubes fresh from Kurtz Quarry
Courtesy of DMS Member Joe Meloney
Photos by Ken Casey |
As 'quarrying' means 'the removal of useful host rock' generally, we collectors actually
'mine' for
specific ore, such as pyrite, dolomite, calcite, and our fluorite. Our club state of
Delaware has no
limestone quarries, yet nearby Pennsylvania boasts scores of them.
(See Above: Map of Pennsylvania Fluorite Locales)
Though there are
no known fluorite locales in Delaware near our clubhouse at Greenbank Mill,
Price’s Corner, it remains to be found just 30 miles or more away in Lancaster
County, PA. Since we
were once considered the "Three Lower Counties" of Pennsylvania, before Delaware
became the First
State, I believe our bond with our neighbors in the Commonwealth still holds strong from
colonial times.
(Yes, I still do remember some of my 4th-grade Delaware History.)
Honing in on our
quarries, let's visit their geology first. Then, we'll take a photo tour of some
amazing specimens collected by our club members and friends.
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| Igneous dike intruding
into limestone layers |
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DMS Fieldtrip, December 2, 2006 |
| Photos from
Burkholder Quarry by Ken Casey |
Pennsylvania Fluorite can be
found in the eastern and south-central regions of the state,
according the Pennsylvania Geological Survey. It has usually formed in the
area’s limestone and
dolostone (karst topography) under high-grade metamorphism by the movement of
magma-heated, hydrothermal groundwater, which travels through brecciations in the host
rock. These natural cracks
play host to water with dissolved minerals and gases, the major constituents being calcium
carbonate and fluorine.
Pennsylvania Regional Karst Map, Courtesy of DCNR,
Pennsylvania Geological Survey
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Other minerals may be
present, which could contribute to the fluorite-formation process. Calcium
and metallic cations, as well as fluorine anions shift bonds in a chemical reaction, which
spurs the precipitation or growth of crystals. Sometimes Magnesium plays a part.
So, we commonly find fluorite crystals, in various stages of
formation in calcite or dolomite veins
within the limestone/dolostone matrix. It has also been found in the serpentine
quarries of Chestnut
Hill, PA.
(Source: Lehigh University
Digital Library Projects: PGS, 48 Pa. Acad. Sd. Proc., vol. XI, pp. 55-57, 1937.)
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| General
geology photos showing prominent formations of Burkholder Quarry (Ken Casey) |
Marcasite and pyrite are generally
associated with eastern Pennsylvania fluorites. South-central
fluorites are more likely to contain more and varied metal-sulfide mineral associations.
Associated minerals to Fluorite in PA are: calcite, quartz,
chalcopyrite, pyrite, sphalerite, hematite, goethite, hydrozincite, malachite, dolomite,
graphite, millerite, etc.
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| Kurtz Quarry from the
top shelf in 2006 |
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Joe Meloney's find-of-the-day
from Kurtz, close-up
(Purple Fluorite, White Calcite, Clear Quartz, Pink Dolomite, Golden Chalcopyrite--all on
limestone!) |
| (Photos by
Ken Casey) |
When we get metal-sulfide
mineral associations, the resulting crystals point towards magma-driven
events. Whether from the heat of contact metamorphism in one stage, to the
subsequent proliferation
of hot groundwater flows, our region of Pennsylvania's mineral wealth culminates in fine
specimens of
our favored Fluorite. Some superb multi-mineral vugs have produced display cabinet
grade material!
For example, a recent Binkley-Ober Quarry
trip at the end of 2006 netted our club President,
Karissa Hendershot, a crystal assemblage of Purple Fluorite, Pink Dolomite, Yellow Barite,
White
Calcite, and metallic Millerite needles--all in one specimen!
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| Sloped folds of limestone
layers |
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Karissa's Millerite needles in
dolomite |
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Karissa's Yellow Barite in
dolomite |
The Binkley-Ober
Quarry hosts limestone geology and some rare finds of fluorite-associated minerals
(Photos by Ken Casey 2006) |
We can't guarantee that
you'll find this hot a rock when you join us, but it speaks to the quality of
finds we generally make over the quarry system each year. So, please do come along
as a member,
and enjoy club collecting.
Most of our Pennsylvania fluorites are found in
Cambrian-Ordovician-aged limestone, faulted and
folded with intense deformation. Limestone and dolostone layers can be see that vary
in composition
of magnesium and silica, with varying crystalline types, and show differing color
variations, from white
to pink to gray. This doesn't mean that the variation of fluorites
are that old, just the host rock.
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The Lancaster County quarries that we visit as a club are officially part of the Lancaster
Valley Section of the Piedmont Physiographic Province. We collect from spoils dug
from two rock units: The younger Epler Formation (485 myo)
of the Lower-Middle Ordovician and the Buffalo Springs Formation
(520 myo) of the Middle-Late Cambrian.
(Left): Geologic Map of Pennsylvania, Courtesy
of the Pennsylvania Geological Survey |
Meckley's Quarry in Mandata,
Northumberland County has massive purple fluorites of a different
age. Its Silurian (443-417 myo) limestones of the Keyser Formation are found
in white calcite and
heavy dark gray limestone. When the landmass was a seabed, strontium-layering later
contributed
toward its almost unique mineralization of Celestite, Strontianite, and Fluorite
deposition.
In comparison to the vastly popular Illinois fluorite locales
of Mississippi/ Early Osagean age
(roughly 354-323 myo), our Pennsylvania specimen host rocks
are grandly more ancient--and are
all the more prized for it! Though their fluorites are measured at having formed
150-120 mya, our's
may be younger.
By this author’s research and
experience, most Pennsylvania fluorites are purple, some having
some rare green also, like those of New Paris. The PGS agrees: “Purple is the
common color in Pennsylvania. Also colorless, white, green, blue, or yellow.”
(Source: http://www.dcnr.state.pa.us/topogeo/education/rocksminerals/es1.pdf)
We'll study in-depth next month in "The Colors of
Fluorite". Stay
tuned!
“In recent years both purple and green fluorite have been
found in calcite veins in the Ormrod
quarries of the Lehigh Portland Cement Co. It is probably this same locality that
furnished the
specimens analyzed and described by E. F. Smith in the following quotation: About one and
a half
miles southeast of the above locality (Ironton iron mines) are the limestone quarries of
Mr. Kieckner.
In them have been discovered veins of beautiful fluorite and fine quartz crystals. The
former mineral
occurs intimately mixed with the limestone, and presents itself in the most beautiful
green, purple
and pink colors. Upon several' specimens octahedral forms were observed, but not very
distinct. It is
seldom that entire crystals can be procured, since blasting is invariably necessary to
reach them; consequently fragments are the result. Quantitative analyses of the purple and
green varieties were
made. Purple variety: Fl 49.20 per cent. Ca 50.87 Fe,O, .. . ...... trace 100.07 The mean
of the
specific gravities of five specimens was 3.21; ranging from 3.17-3.24. The shade of purple
varied very
much in the specimens examined. Green variety: Fl 49.0.0 per cent. Ca 50.91 Fe20, trace
99.91 Sp.
gr. about the same as in case of the purple. South of Emmaus in the Lehigh mountains Mr.
Benj.
Sadtler, Jr., found this mineral in perfect octahedra of deep purple color in a granitic
rock. (Smith,
1883, p. 272.) The rather widespread but sporadic occurrence of small particles of
fluorite in both the pre-Cambrian and Paleozoic strata of the State brings up the question
of its origin. Although at the
present time there seems to be a preference among geologists for the belief in magmatic
waters as
the source, the writer strongly inclines to the belief that most, if not all, the
occurrences of fluorite in
limestone known to him within the State have been formed by artesian waters of meteoric
origin.”
(Source: http://digital.lib.lehigh.edu/lvgeology/_588.html)
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| Green &
Purple Fluorite, New Paris, PA |
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Purple Fluorite,
New Paris, PA |
| (Photos
by Ken Casey 2007) |
This is most I have been
able to find online to date, as to the specifics of Pennsylvania Fluorite
geology. Since more would be beyond the scope of this article, I would suggest for
any good
researcher to hit the stacks in college libraries for more. I know I will.
Likely, Mr. Miller’s observations are exciting as to
occurrence; however, I would suggest his
theory upon its formation to be valid only in some instances. Though, I would offer
that the hydrothermal
process is more likely in most.
Clear and colorless 1mm cubes from the Wheatley Mine,
Phoenixville, PA, were analyzed at the
American Museum of Natural History in 1931. Quantitative results of this
well-provenanced sample
suggest a pure calcium fluoride (Calcium, 50.81% and Fluorine, 48.29%).
(Source: http://digitallibrary.amnh.org/dspace/bitstream/2246/3843/1/N0472.pdf)
According to the USGS Commodity Inventory by State:
Pennsylvania (January 3, 2000), Fluorine-
Fluorite’s value is nil. Though it is not a mined stone, like the fluorspar in
Tennessee,
collectors still find it valuable.
(Source: http://minerals.er.usgs.gov/fact-sheets/MRDS_STATISTICS/STATEFILES/PA.HTML)
Our club’s recent collecting experience has lead us into
the purple fluorites of several Lancaster
County area active limestone quarries: Binkley-Ober, Kurtz, Prospect Aggregates,
Burkholder, and
farther north and west, Meckley’s Quarry in Mandata, Northumberland County.
Meckley’s fluorite crystals are usually subhedral or
euhedral; whereas, the other four quarries
contain well-formed cubes, some gemmy in appearance.
New to our MOTM format is an offering to you of two museums of
note. Of course topical, I
suggest two museums to expand your tour: one local, and one with an internationally
impressive
collection. So, here's to the Iron Hill Museum in Newark, Delaware and the Carnegie
Museum of
Natural History in Pittsburgh, Pennsylvania. Cheers!
Our local museum is a friend to our club, The Iron Hill Museum. Under the auspices of
the
Delaware Academy of Science, Director Laura Lee was kind enough to loan briefly some
massive
Fluorite specimens for a top-notch display case in our March 3-4, 2007 Show.
Our museum of world fame is the Carnegie Museum of Natural History. With
their $20,000.
acquisition of PA Fluorites, their Hillman Hall collection boasts superb old finds for us
to view.
William W. Jefferis of West Chester, PA, sold his massive
collection to the Carnegie Museum of
Natural History in 1904, which contained several fine Pennsylvania Fluorite specimens.
Jefferis was
a contemporary of James D. Dana, whose System of Mineralogy holds several specimen
pictures
from Mr. Jefferis' collection. (Source: "History of Hillman
Hall", Carnegie Museum of Natural History)
The "Masterpiece Gallery" has had several
outstanding purple fluorite on white quartz specimens,
since 2003.
One can also find Fluorite prominently displayed in the
collections of the Yale Peabody Museum
and the Irénée
DuPont Mineral Museum at the University of Delaware.
As we fellow MOTM-trekkers already know, we have visited Fluorite on two other occasion
in:
January Mineral of the Month:
Fluorite June
Mineral of the Month: Antarctic Fluorite, both in 2005.
In these articles, we have covered fluorite's uses across the board. As we are
concentrating on
Pennsylvania Fluorite, I could say that the only two uses are: to enjoy as specimens, and
to act as
an extremely minor constituent of rip-rap or cement. That's what the quarries who
encourage us to
visit with them do with their raw materials. Thanks to all of the quarry owners and
staff, who so
generously let us advance our interests in geology education!
So, in the spirit of
sharing uses, please enjoy this photo sampling from our club's past four years
of collecting:
Hillman Hall at the
Carnegie Museum of Natural History
Penn State Earth & Mineral
Sciences Museum and Art Gallery
Virtual Mineral
Exhibit at the New York State Museum
Irénée DuPont Mineral
Museum, University of Delaware
Peabody
Museum of Natural History, Yale University
Here is where DMS Members can add their nice
Fluorite photos to share with us.
Until Next Time
We hope you have enjoyed our quaint visit to Pennsylvania
Fluorite. Please join
us next month, for another article, and we shall journey together!
Until then, stay safe, and happy collecting. 
Article Contributors
Benjamin Miller
Joe Meloney, DMS Member
I would like to gratefully acknowledge the generous contributions of our fellow PA
Fluorite
enthusiasts,
collectors, authors, curators, professionals, and club members who made this
work possible. Thanks.
©2007 All contributions to this
article are covered under the copyright protection of this article
and by separate and several copyright protection(s), and are to be used for the sole
purposes of
enjoying this scholarly article. They are used gratefully with express written
permission of the
authors, save for generally-accepted scholarly quotes, short in nature, deemed legal to
reference
with the appropriate citation and credit. Reproduction of this article must
be obtained by express
written permission of the author, Kenneth B. Casey, for his contributions, authoring,
photos, and
graphics. Use of all other credited materials requires permission of each
contributor separately.
Links and general contact information are included in the credits above,
and throughout this article.
The advice offered herein are only suggestions; it is the reader's charge to use the
information
contained herein responsibly. DMS is not responsible for misuse or
accidents caused from this
article. All opinions, theories, proofs, and views expressed within this article, and in
others on this
website, do not necessarily reflect the views of the Delaware Mineralogical Society.
Suggested
Reading:
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About
the Author: Ken is current webmaster of the Delaware
Mineralogical Society. He has a diploma in
Jewelry Repair, Fabrication & Stonesetting from the Bowman Technical School,
Lancaster, PA, and worked as jeweler. He has
also studied geology at the University of Delaware. And,
he is currently a member of the Delaware Mineralogical Society and the Franklin-Ogdensburg
Mineralogical Society. E-mail: kencasey98@yahoo.com.
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