Our March Mineral-of-the-Month is Calcite. It has more forms than most other
and, that is what we will concern ourselves with in this article. We will touch
lightly upon its
science and chemistry, but will mainly focus on the variety of magnificent forms its takes
nature. This article is by no means comprehensive on the subject, as many volumes
neededpossibly a lifetimes work could be devoted to this favored
mineral. So, we will embark
upon an odyssey of form and function, to places wherein the calcite can surround us in
voluminous, echoing spaces. Also, we shall visit locales that I hope will enjoin you
to visit, and in
some, collect your own specimens of this awesome wonder.
As you might expect, our journey today takes us not only into
the basic science of Calcite,
but into its surface, underwater, and underground homes. We will visit pinnacles,
caves and vugs,
as well as exotic and common crystal forms around the United States and parts of the
Among these places are ancient caves around the U. S. and Spain, curious vugs in Alaska,
a virtual tour of enticing crystals from around the world.
Inside Carlsbad Caverns, New Mexico
some calcite enthusiasts, crystals are the key to their excitement about our hobby.
others, visiting the naturally air-conditioned, underground sites suits their fancy.
Purveyors of fine
specimens might agree that no matter what the source, calcite has a lure all its
|Calcite, Sweetwater Mine,
Reynolds County, MO
||Bear Creek Research Area, AK
||Calcite from Franklin, NJ
|Courtesy of: Isaias Casanova
||Dr. Michelle M. McGee
From a quick viewing of photos on this page, we can witness outstanding rhombs and prisms,
free-form speleothems, and encrusted vessels of this crystallized carbonate, famously
Our journey continues with a larger than life experience, as we might imagine our
us into the cheery, mega-vugged tunnels of near darkness, wondering what odd
form we may find
around the corner on our caving tours.
Before any spelunking, however, it is helpful to have a basic understanding of
forms, and habits to appreciate the wonders we will see below. As always, remember
to put on
your hard hat!
is calcium carbonate (CaCO3). The
name calcite derives from the Greek word for lime,
etymology progresses from Greek to Latin, then to Middle
English, from Old English cealk,
from Latin calx,
lime; see calx
you may see a package of lime labeled: calc, calce, kalk, chaux, wapno, or bap.
©2005 Crayola, Easton, PA
||Cal Agricola (Agricultural Lime)
Caleras de San Cucao, S. A., Asturias, Spain
Calcite crystals, caves, vugs all have their own geology. Still, all remain chemically the same,
except for the occasional atomic addition of cations that can share or replace the calcium
These natural substitutions, included by the environment in which they formed, can affect
appearance of this mineral. For example, the
presence of Manganese (Mn) can offer a pinkish cast,
hence it is named a variety of calcite, called manganocalcite (Ca, Mn)CO3. There are other varieties,
but we will stick with just a few here.
||2067. Calcite Var. Manganoan Nikolayevskiy Mine,
Dalnegorsk, Russia (10.5x7x6 cm)
Courtesy of IC Minerals
To touch upon its crystallography, calcite belongs to: Crystal system: hexagonal.
three-directional in rhombohedron-shaped fragments. Color: usually white, but may be
colors by impurities. Hardness: 3.0. Luster: glassy. Specific gravity: 2.71.[iii]
Calcite can form twins and trillings, whereas aragonite can form pseudomorphs (false
after other minerals, such as glauberite crystals[iv], agate fillings[v],
and aragonite fans in fossil
stromatolites[vi]. Polymorphs include: vaterite. Flosferri is the free-form of aragonite.
|Mostly, aragonite decorates cave
interiors, such as these stalactites in Lost
River Caverns, Hellertown, PA.
Images courtesy of Mr. Gilman, Lost River Caverns
Calcite cleaves and crystallizes in rhombs of differing measures. The CaCO3 of calcite and
aragonite differ by noting that the radius ratio of Ca:O (=0.707) in CaCO3
is so close to the limiting
value between 6 and 8 coordination (0.732) than CaCO3 can occur in two
structure types: calcite with
6 coordination of Ca to O and aragonite with 9 coordination of Ca to O.
(Dana, p. 297)[vii]
Like fluorite, [m]ost calcites tend to be relatively close to pure CaCO3
with CaO 56.0 and CO2
44.0%. Mn2+, Fe2+ and
Mg may substitute for Ca and a complete solid solution series extend to
MnCO3 (Dana, p. 298)[viii]
For more on Calcites crystal morphology and science, visit Amethyst
Galleries: The Mineral Calcite
on its paragenesis, calcite can take up almost any color from elements present at
its origin. Colors range from red, orange,
yellow, green, blue, white, gray, and colorless. Sometimes
it occurs as multi-colored. Chemically, it
starts as basic [c]alcium carbonate, commonly with some
impurities of either iron, magnesium, manganese, and occasionally with zinc and cobalt.
impurities do not exist together, they are all listed together in the "Variable
Formula" field [of the
to avoid confusion. (See the Brownspar Group
for more information.)[ix]
is a rock-forming mineral, and can be found in sedimentary limestone, metamorphic marble,
and chalk deposits. There are siliceous
calcites in South Dakota, and calcite is an igneous constituent
in carbonatites and nepheline syenites. Other
occurrences include crystals in lava cavities and in hydrothermal veins associated with
(Dana, pp. 299-300)
is so common on all continents, that even rare igneous carbonatites containing calcite
been found in the Transantarctic Mountains of southern Antarctica.[xi] And we have yet to scratch the
surface, which has only 2% rock outcroppings visible out from the glacial ice.
Pyrite, chalcopyrite, fluorite, dolomite form massively, or as crystals, within our
quarries. Calcite also occurs with apatite,
barite, gypsum, dolomite, quartz, and wollastonite (formed
from CaCO3 + SiO2 à
CaSi3 + CO2). In Sussex
County, New Jersey, it occurs with 358 zinc ore
related minerals, most notably, franklinite, willemite, and zincite, in the calcite-like
|Gray Tremolite crystals
in Franklin Marble
||Salmon Calcite, Franklin, NJ
||White Calcite, Red Willemite,
and Black Franklinite
Photos by Ken Casey © 2005
seems that calcite can be used in most any product, from building construction to teaching
supplies to foodstuffs. The obvious building
material is concrete, cement block, and natural
dimension stone, such as limestone, marble, and travertine. In the classroom, we witness calcium
carbonate as paper surface-hardeners upon which our ballpoint pen writes cleanly, and as a
narrow cylinder used for writing, also known as chalk. Dietary supplements include antacids and
chewing gum covering.
It also has these [u]ses: in the form of limestone, as aggregate for road surfacing
agricultural lime, flux, building stone, sulfur sorbents, and in cement; in the form of
Iceland spar in
optical instruments to obtain polarized light.[xiii] Even iron-ore smelting requires some.
would guess that we employ calcite in animal feed, to strengthen dough, in baking powder,
in glass making, or in photography and waste treatment plants.[xiv]
We use calcite to build upon a grand scale. For millennia, limestone and marble have
been the building
stone of choice for much of the world's great
architecture. From the Egyptian pyramids and Greco-Roman temples of the past to
today's modern government and office buildings. Many of the federal buildings in
Washington, D. C. are either built with or are faced with limestone. The U. S. Capitol is one of these. In the 1950s, though, the building received a
much-needed upgrade from limestone to marble. This
façade should last at least another 100 years.
depend on this multipurpose compound for use in everyday products; and for some, for their
livelihoods. Our club has had the good
fortune to visit many rock quarries on our fieldtrips to see the
active quarrying and mining processes, as well as to collect various types of calcite.
form into calcite, aragonite, Iceland spar, and into microcrystalline travertine, tufa and
It metamorphoses into limestone and marble. Varying
cave forms are common, and pseudomorphs
and polymorphs abound.
those who admire faceted crystals, calcite can demonstrate many forms, the most common
being prisms, rhombs, scalenohedrons, trillings, and twins. This author has not yet
there is a direct, consistent link of color to crystal form, though believes it is worthy
We most see calcium carbonate crystals as white, colorless, yellow, tan, gray, and salmon
colored in our region. The first three
colorations predominate eastern Pennsylvania limestones,
whereas, the second three are likely found in northern New Jersey. The latter tend to fluoresce
under ultraviolet lamps.
|Salmon calcite, Franklin, New
||Salmon Calcite rhomb
||White Calcite rhomb (Franklin
Photos by Ken Casey ©2005
Our clubs fieldtrips have rewarded us with magnificent crystals of up to one-inch in
Some of the best are colorless, singly-terminated scalenohedral variations. Here are examples
from the Kurtz
in Denver, Pennsylvania.
|White Calcite, Milky Quartz vein
in Kurtz Limestone
||Clear and Milky Calcite, Pink Dolomite,
and Purple Fluorite vug, Kurtz Quarry
Photos by Ken Casey ©2005
our clubs general collecting range lies numerous locales that popularize this
mineral. One of our March Show
vendors, Isaias Casanova of IC
has generously lent
some of his calcite collection photos for us to wow over.
Karstic activity spawns travertine and tufa as groundwater is forced through limestone as
earths carbon cycle. In
many locations with karst, CO2 emission is associated with the deposition
of calcareous sinter (e.g., tufa and travertine) at the outlet of cold or warm springs (Berger
It is amazing that [a] fifth of the
landscapes in the United
States are karstic. Major karst areas
occur in 20 states, and smaller karst regions occur throughout the nation. Many major
underlain in part by karst, such as Saint Louis, Missouri; Nashville, Tennessee;
Alabama; and Austin, Texas.[xvi]
||Calcite Jungle at
Cave of the Winds, South Dakota
||Cave-divers at John Eddings Cave
NPS Photo by Carol Bitting
Courtesy of the National Park Service (NPS Photos)
Undersea caves also exist to visit by engaging in the extreme sport of cave diving. These exist
as most limestone is of marine deposition. Orogenies
(mountain-building events) have pushed ancient
layers to the surface.
Erosion and groundwater take their toll, thus forming the terrestrial tunnels that we
the possibility of continent-wide cave formation, travertine and tufa deposition, and
metamorphic calcite crystal vugs leaves us many locales to explore. Let's go!
I will begin by introducing some above ground calcite formations.
forms from underground magma that geothermally heats mineral-laden water springs.
The resultant rising steam pressure forces the superheated water to the surface, where it
leaving behind thin layers of accumulating travertine.
A good example is Mammoth Hot Springs
Park. The park covers the borders of three states:
Idaho, Montana, and
|Picture of hot springs and
resultant travertine, Yellowstone National Park (NPS Photo)
A cool site to visit is the Old Faithful Geyser webcam. Its the next best thing to watching the
travertine form in person.
is formed as cold water dissolves surrounding calcareous rocks. As the water flows, it leaves
calcite to deposit as microcrystals. Iron
oxides may accompany the calcium carbonate, thus
resulting in red and yellow staining of the newly formed layers. Sometimes, plants and animals can
become trapped and coated to later form fossils.[xvii]
Rocky Mountain region contains various tufa topographies.
Some tufa (pronounced toofa)
examples are found in the Trona
Pinnacles National Natural Landmark
near Argus, California.
Utahs Lake Bonneville shoreline consists of Pleistocene sedimentary tufa, whereas
the tufa towers
California have formed of spring water mixing with lake water.[xviii]
chemical reaction precipitates into slow growing towers.[xix] The bases begin near or under
the lake waters, and build from there upwards.
|Tufa deposits at Trona Pinnacle National Landmark,
California (NPS Photo)
resembles onyx, however, it is actually calcium carbonate.
It goes by locality
names, such as Mexican onyx from Baja and Mt. Nebo
from Utah. The Mt. Nebo
consists of reddish-orange and cream-colored banded calcite. Calcite is composed of
carbonate (CaCO3). Banded calcite is formed when calcium carbonate precipitates
from a solution of dissolved calcium carbonate and ground water. The calcium carbonate is
within a large opening or fissure in the mother rock and parallel bands are created as
calcium carbonate precipitates.
|Mt. Nebo Onyx
Calcite alabaster vase
Photo by Ken Casey © 2002-2005
||U. S. Department of State
The changes in the color banding are probably caused by slight changes in the
composition of ground water during precipitation. The Mt. Nebo banded calcite can be
used for decorative purposes, such as bookends.[xx]
Alabaster is known as a form
of gypsum. It also refers to a similar
looking rock form of calcite,
and is used for the same purposes: decorative carving. (See 'alabaster vase' photo
We will now go underground, traversing through the cave mouth, and climbing downward on a
mild slope, until we reach our first of natures decorations. Watch your step!
forms crystals in vugs and stalactites/stalagmites (varieties of speleothems), and in
caves as calcite or aragonite. It may contain
strontium, lead, or zinc, as well.
Cave formations are called speleothem, from the Greek word "spelaion",
cave and "thema"
meaning deposit. Almost all of them are made of calcite, the crystal of calcium
Different minerals and different movements in the water account for an incredible variety
|Aragonite speleothem pictures:
cave bacon, flosferri, and stalactite/stalagmites
Various National Park Service Caves (NPS Photo)
are cave formations. Specifically, the term is applied only to deposits formed
from a chemical solution or by the solidification of a fluid after the formation of a
are speleothems, as are ice crystals formed directly form water vapor in a cave; but beds
and calcite veins etched into relief when the walls of the cave dissolved, are not.
and Sullivan (1997)[xxii]
These form in solution caves, in which acidic groundwater travels through
cracks and dissolves limestone. The flow then
drips down from cave ceilings to create stalactites.
The falling water then hits the cave floor, hence building up stalagmites. One mnemonic device to
remember which is which, is to use a differing letter in the third syllable of each term. Use T for
stalactite (it looks like it is pointing down, and M for stalagmite (the humps
on the M appear to
be pointing up).
Incrustations can form as the mineral-laden ground water drips and runs over the cave
topography. These form curving, translucent
shapes resembling strips of bacon, animals, and
pipe organs, to name a few. Sometimes these
curious forms are obvious; often, they require
ones imagination. Cave tourism is built
upon our curiousity to witness these imaginative sites.
There are many such caves open to the public for a fee to tour in our
clubs area. Two
examples are: Lost River Caverns in Hellertown,
Pennsylvania and Crystal Cave Park in
Only one known real cave exists in our state. It is the Beaver Valley Cave in New
Delaware. However, advanced caving skills are required, and the only current access
the Commander Cody Caving Club.
I visited the Lost River Caverns about three years ago, and the
tour was most fascinating. It is a good day trip for families, groups, or
is riddled with caves found in most states. There are too many to list
here, so I will suggest a few outstanding examples, along with those administered by our
National Parks Service. You will find the list below.
Some people live in
caves. Both ancient and modern man share this distinction as
The historic cave paintings of Lascaux Cave
in France support this hypothesis. Other
the world have also left evidence for us to ascertain this fact. Neanderthal man has called them his
home in Europe and the Middle East.
Today, some still enjoy their digs underground. In
Spains Andalusia region a whole community
is situated in them. The Cuevas Galera Complex
touts modern conveniences, as well. There are
comfortable abodes nestled in the mountains and plains of the United States. For
example, two such
established living quarters comprise the bulk of a cave entrance in Parthenon, Arkansas,
and one in Armington, Illinois.
More information may be
found on the Home & Garden Television website.
Just search for the
show Extreme Homes episodes: EXT-314,
or search for (cave AND home) for a listing.
There is even a bed-and-breakfast at Kokopellis
Cave in Farmington, New Mexico. Just reference
Dream Builders episode DRB-801
Some 19th & 20th
century American outlaws would hideout in caves. Treasure hunters have
recently uncovered relics of the fugitives who stayed in one Oklahoma cave. The Knights of the
Golden Circle and Outlaw Treasure website offers us a view of famous cave-dwelling
wondering into a cool, dank cave ecosystem, you may find the inhabitants (troglobites).
You might feel silent air currents, signaling a larger cave beyond. The average annual surface
temperature will be how cool your skin will feel while exploring. Many U. S. caves hover around
55 degrees Fahrenheit. So dress warmly on
You may forget your initial reaction to your new environs, as you extend your experience
visualthe lighted passageways beckoning you, along with your tour guide calling you
to move inside toward these fantastic natural wonders.
For the spelunker (cave explorer), you must bring your own illumination and gear.
You may wish to explore these caves below. Let's go in!
|Entrance to Carlsbad Caverns, New Mexico
||Lanterns to light our way
||NPS Ranger giving
Courtesy of National Park Service Photos
National Caves Association
The Caving Pages
National Park Service Cave and Karst
Caves to Visit
Cave of the
Winds, Manitou Springs, CO
Lost River Caverns, Hellertown, PA
Crystal Cave Park, Kutztown, PA
Skyline Caverns, Front Royal, VA
Luray Caverns, Luray, VA
Butternut Valley Virtual
Nature Reserve, TN
Russell Cave National Monument, Bridgeport, AL
Mammoth Cave, KY (not NPS
Marengo Cave, Marengo, IN
Cave of the Mounds, Blue Mounds, WI
Onondaga Cave State Park, Leasburg, MO
Wind Cave National Park, Hot Springs, SD
Jewel Cave National Monument, Custer, SD
Carlsbad Caverns National Park, Carlsbad, NM
Timpanogos Cave NM, American Fork, UT
Caves of the
Caves to learn
Caves at Mt. St. Helens Crater
Crystal Ball Cave, Millard
Lascaux Cave Paintings,
Lava Beds National
Sequoia and Kings Canyon National Park
Pinnacles National Monument
Craters of the Moon
Ozark National Scenic River
El Malpais National Monument
Jewel Cave National Monument
Wind Cave National Park
Timpanogos Cave National Monument [xxiii]
Mammoth Cave's "Broadway"
is a vug? Vug is derived from a Cornish term, 'vuggh', meaning crystal-lined cavity. The
mines of Cornwall, England, have produced metal ores and mineral specimens since the 5th
so many mining terms are of Cornish origin.[xxiv]
The vugs we will be exploring contain phenomenal calcite crystals. These
small caves can
house well-preserved crystals for eons, mainly because vugs are usually sealed off from
air and weather. Usually, it is the fortunate rockhound who breaks open a likely
candidate boulder to
expose beautifully faceted calcite crystals. Our club has visited two limestone quarries this past year
to find varieties of clear, white, and yellowish terminated crystals.
The limestone of both the Kurtz and Binkley-Ober quarries is hard to
work, but worth the effort.
The products of our hosts are aggregate and concrete block, respectively. Having a
of local geology can assist both the experienced and novice field collector. The
purpose for the quarrys
output can be a guide the relative hardness of the local stone. Also, by
ascertaining the general
porosity of the host rock (matrix), one can project the possibility of vugs to increase
his or her chances
of opening ones with calcite crystals.
This sample research, conducted by the Laboratory for Computational Geodynamics
University, shows the approach to advanced geology and materials science. It is your choice as to
how much you would like to learn to enhance your rockhounding experience.
Calcite-dolomite host rock with porosity of 0.20. The stresses are normal overburden
and fluid pressure is hydrostatic with water table at the surface of the basin. Horizontal
computed by constraining the lateral displacement. Highly asymmetric vugs survive below
meters when oriented vertically, but the ones oriented vertically fail after 1100
Chart of porosity test
Laboratory for Computational Geodynamics, Indiana University
Michelle McGee, graduate of the University of Alaska, has conducted field research in
the limestones of northern Alaska. The Bear
Creek Field Area plays home to many small caves
and calcite-lined vugs. The crystals formed
around other fossilized marine organisms, such as
These photos are of the Carboniferous lower Lisburne Group in
the Arctic National Wildlife
Refuge (Northeastern Brooks Range), Alaska." --Dr. McGee
The Lisburne Group is a thick
sequence of Carboniferous carbonate rocks present in Alaskas
North Slope subsurface and exposed in the adjacent Brooks Range.[xxvi]
[Modified from: McGee, M.
M., and Whalen, M. T., Stratigraphy of the Carboniferous Lisburne
Group, Porcupine Lake Valley, Brooks Range, Arctic National Wildlife Refuge, Alaska
American Association of Petroleum Geologists Pacific Section meeting, Anchorage, AK, May
2002, p. 91 (poster).]
Dr. Michelle McGee has her Ph.D. from the
University of Alaska, and currently is a geologist
for Core Laboratories.
To review the details of her completed research: McGee, M.
M., 2004, research page online.
Carboniferous Lisburne Group Carbonates of the Porcupine Lake Valley: Implications For
Subsurface Sequence Stratigraphy, Paleogeography, and Paleoclimatology, Ph.D.
University of Alaska Fairbanks, 453 p., or visit her
Calcite crystals in Pennsylvania's limestone quarries occur mostly in fist-sized vugs, to
club's recent collecting experiences. These are the yellow-tan dog-tooth spar and
scalenohedroal variations. Some white, massive calcite occurs with quartz and
The Kurtz Quarry produced some nice
assemblages of calcite, pink dolomite, purple fluorite, and
Calcite is soft, measuring 3 on Mohs Scale of Hardness, thus making it suitable for
and ease of polishing. Spheres are the
predominant form lapped today. Others make
and beads. I have seen bookends crafted of
Mexican onyx, and hope to create a work from my
very small sampling of Mt. Nebo banded onyx. Perhaps
you will get some ideas from the
materials presented here.
As some favor different materials, such as Utah honeycomb calcite cabbing rough, or
Shaba Congo cobaltan calcite for cabs, others might facet gemmy rough for sparkling
grace their jewelry. The colors and
tradenames seem endless, so there is a specialized appeal for
many lapidaries practicing today.
Derbyshire, Durham, Cornwall, Lancashire, England
Mountains (Vicenza), Italy
Molignon (Valdi Fassa, Trento), Italy
Superior copper district
Lewis County, New York
quarries near Riverside, California
of Durango, Sonora, Sinaloa, Mexico
Hill and Paterson, New Jersey
Mine, Reynolds County, Missouri
partial list was compiled over time.)
caving lore is beyond the scope of this article, it might help to mention a few words
and phrases to capture your interest for further research and entertainment: Neanderthal,
outlaws, petroglyphs, Batman, mythology, gateway to the underworld, the movie
Journey to the
Center of the Earth, H. G. Wells hungry Morlocks, who snack on Eloi (The
Time Machine, both
the movies and the book), Mars exploration, our first homes underground, The Flintstones,
Dr. Who. The list could be endless. I bet you have thought of a few of your own to
NM (NPS Photo)
I hope you have enjoyed our journey around calcite and all its many forms. When you think of
calcium carbonate now, perhaps you will desire to find your own crystals, caves, and vugs.
Remember to extinguish your lanterns and stow your hardhats! Until our next
Hurlbut, Jr. and Cornelis Klein, Manual of Mineralogy (after
James D. Dana), 19th edition, London: Longman Group Limited, 1976, p. 297.
[viii] Hurlbut and
Klein, p. 298.
[x] Hurlbut and
Klein, pp. 299-300.
Isaias Casanova, IC
Dr. Michelle M.
United States Department of the Interior, Bureau of Land Management,
National Park Service (NPS Photo)
I would like to gratefully acknowledge the generous
contributions of our fellow calcite
collectors, authors, curators, professionals, and club members who made this
work possible. Thanks.
Isaias Casanova, IC Minerals
Dr. Michelle M.
United States Department of the Interior, Bureau of Land Management,
National Park Service (NPS Photo)
All contributions to this article are covered under the copyright protection of this
and by separate and several copyright protection(s), and are to be used for the sole
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
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,
graphics. Use of all other credited materials requires permission of each
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
Exploring Hidden Realms by Michael Ray Taylor and Ronal C. Kerbo
Exploring Caves: Journeys Into The Earth by Nancy Holler Aulenbach and Hazel Barton
Beyond the Deep: The Deadly Descent Into The World's Most Treacherous Cave by Monte
No. 4: Calcite
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: email@example.com.
Amethyst Galleries, Inc. The Mineral
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A-113 Aragonite pseudomorph after
Glauberite. 28 Feb. 2005
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Agate. 27 Feb. 2005
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of Mineralogy (after |
James D. Dana), 19th edition, London: Longman Group Limited, 1976.
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14-20 September 2001. 26 Feb. 2005
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