Preface Introduction Chemistry & Science Crystals Uses Dolostone Geology Lapidary Endnotes Article Contributors Photo & Graphics Credits Suggested Reading Webliography Invitation to Members Past Minerals of the Month		Cerussite with Smithsonite on Dolomite Tsumeb Mine, Tsumeb, Namibia	Curved Crystals of Dolomite
		Dolomite is much overlooked in the mineral kingdom...
		...until now!
		The above images are courtesy of Isaias Casanova of IC Minerals ©2005 and Stand Celestian of Glendale Community College ©2005

Preface

     In a two-part series (this month and next), we will explore Dolomite as our Mineral-of-the-Month. 
More specifically, in part 1, we will explore Dolomite crystals and Dolostone.  In part 2, we will
embark on a journey to New York State of the famous “Herkimer Diamonds” and their dolostone
matrix host.  Uses from crushed stone to recreating over karst topography will be covered.

     Being in the Calcite Family, Dolomite offers remarkable assemblages of crystals from its
related limestone-dolostone host.  Of course we will begin with dolomite science.  Then, we will
touch upon the geologies of both Pennsylvania and New York States, as they relate (from west
to east) to Niagara Falls, Herkimer County, New York, and Eastern Pennsylvania.  We will
compare a few dolomites from around the world from select locales.  Then, from a little
ecotourism to field trips to crystals and collecting, we will travel from west to east, arriving back
at our clubhouse in Wilmington, Delaware.  So grab your hardhat, and lets embark!

    Well, it looks like everyone is present and accounted for.  Everyone has their safety gear,
and we have all met up on time at the Schoellkopf Geological Museum in Niagara Falls, New
York.  Let’s go!

     Our first stop is here at the museum to learn of the basic geology of the Niagara Gorge. 
Next, we will explore the riverbank on a special trail, then arrive back at the museum to drive
to our next spot, Herkimer County, New York.

Niagara Falls, Photo by Niagara Falls State Park	Tan dolomite crystals, Herkimer, New York

Dolomite Chemistry & Crystallography

     Dolomite, which is named for the French Mineralogist Deodat de Dolomieu, consists of
calcium magnesium carbonate or CaMg(CO₃)₂.[xiii]

     “Pure dolomite contains 54.28 percent calcium carbonate and 45.72 percent magnesium carbonate.”[xiv]

     Concerning dolomite’s crystallography, crystals typically form rhomobhedral (Hexagonal
System), curved saddle-shapes in groups.  Generally occurring as pink pearl spar, it can
occur in clear, white, gray, tan, or black, depending on its formation with related carbonate-
forming cation substitutions.  For example, with a substitution of iron (Fe) for magnesium (Mg),
brownish ankerite, Fe(CO₃)₂ crystals will form.[xv]  Our club has collected such ankerite
crystals from eastern Pennsylvania.

     With a relative hardness of 3.5-4, its differentiation from calcite can be determined by
acid test.

Brown ankerite on gray dolomite boulder from Phoenixville, PA, nearly cabinet-ready Photo by Ken Casey ©2005		Rhombohedral Dolomite Crystal Photo by Stan Celestian ©2005

Crystals

Dolomite (Hexagonal) Rhomb		Dolomite Steep Rhomb & Base		"Dolomite Saddles" in Dolostone Matrix
(Drawings by Ken Casey © 2005)

Classic pink crystals of Dolomite from the Tri-State mining district near Joplin, Missouri Photo by Stan Celestian © 2005 Glendale Community College, Glendale, Arizona Specimens provided by the Arizona Mining and Mineral Museum, Susan Celestian, Curator

Rhombohedral Dolomite Crystal Twins			Clear and Milky Calcite, Pink Dolomite, and Purple Fluorite vug, Kurtz Quarry
Photo by Stan Celestian ©2005		Photo by Ken Casey ©2005

Uses

    “Dolomite and dolostone are used for nearly all the same purposes as calcareous
limestone; however, the additional magnesium content allows other uses.  In the case of
dolomite rock or ‘dolostone’, the calcite, quartz, and feldspar constituents together form
a tougher dimensional stone.

     “The most important use of dolostone for which limestone cannot be substituted is in the
manufacture of refractory dolomite and in the preparation of heat-insulating materials.
Limestones and dolostones high in silica are suitable for the manufacture of mineral or rock
wool for insulation.”[i]

     “A source of magnesium metal and magnesia. Also used in as an aggregate for cement
and as a flux in blast furnaces. When dolostone is used a flux, the resulting slag can be
reused for light-weight aggregates and the like, because dolostone slag does not disintegrate
in water as limestone slag does.

     Dolomite is used in manufacturing cement, in addition to being an ornamental stone. 
Dolomite is a major ore from which magnesium is separated, which in turn is burned for use
in a variety of lighting applications, such as photography and pyrotechnics.”[ii]

    “Dolomite is used to make magnesia, which has important medicinal applications.
Dolomite specimens from the Picher, Oklahoma area are very popular among mineral
collectors and dealers. The clear transparent specimens from Spain are rare and unusual,
and are in high demand by collectors.

     Dolomite Rock is used as an ornamental and structural stone, and for extracting certain
metals from their ores. It is useful in the chemical industry in the preparation of magnesium
salts.”[iii]

     For example, a western Pennsylvania company, Moore & Moore in Portersville, hauls
and spreads both dolomite and calcium limes for customers.[iv]

     On the other side of the state, “[t]he Middle Cambrian Ledger Formation in eastern
Pennsylvania is a high purity, single-stage-sintering dolomite. It yields high quality, direct
bonded, environmentally clean, doloma bricks for steel, cement and lime industries use.”[v]

For recreation one might attempt to traverse the Italian Dolomite Range of mountains.  According to authors Kohler & Memmel in their book Classic Dolomite Climbs, a mountaineer could ascend “multi-peak traverses, long middle-grade classics, multi-pitch high-peak challenges & free-climbing testpieces.”[vi]      Even coal-mining reclamation in the United States can benefit from the presence of dolomite.  In the coal-mining regions of Pennsylvania, a process called ‘alkaline addition’ is argued to curb the acidity leaching from mine tailings into the environment.

     “The addition of alkaline material, usually a limestone-derived waste product, to surface
mine backfills can be an effective method of compensating for overburden that is naturally
deficient in neutralizers.”[vii]

     “Carbonate minerals play an extremely important role in determining postmining water
chemistry,” as “both calcite and dolomite will neutralize acid, and potentially inhibit pyrite
oxidation.”

     In eastern Pennsylvania, dolomite/calcite rich Pleistocene glacial till has been deposited
to aid in the process.  “In summary, glacial overburden can be beneficial in preventing acid
mine drainage if it is calcareous. Because of the small grain size, unlithified nature, and the
source of carbonates in glacial sediments, the NP determinations of glacial overburden
probably more accurately reflect the ability of the glacial sediments to prevent and neutralize
acid mine drainage than is sometimes the case with bedrock overburden.”[viii]

     Since a clean groundwater source is important to both nature and man, the protection
of aquifers and our karst topographies is of paramount importance to our survival.  Dolomite
and dolostone, by their very nature, erode via the hydrologic cycle, from a mild, acidic rain. 
This runoff over our watersheds, seeps into the bedrock to promote the formation of caves
and subterranean rivers.

     Dolomite and dolostone also serve us above ground, as well.  The Niagara Gorge and
Escarpment development over the last few thousand years has yielded a grand, natural
phenomenon known as Niagara Falls.  A popular tourist attraction spanning the U. S. at
New York and Ontario, Canada, these water features arouse awe, wonder, and hydroelectric
power.

     The famous twentieth-century scientist, Nicola Tesla, designed the power plant that still
serves the electricity needs of two nations.  In fact, the flow of river water over the falls is
regulated to provide optimum power and tourist satisfaction over a day-night cycle.

     This author learned all this while visiting the falls and the Schoellkopf Geologic Museum
in Niagara Falls, New York.  Situated right on the river gorge, this museum specializes in
the makeup of the falls.  For more on the lore of the falls, other popular museums may be
found in the area.

     In our club’s area, many organizations are making a positive impact to preserve our
supportive karst.  For example, in 2004, the National Fish and Wildlife Foundation has
granted funds to the “Bucks County Chapter of Trout Unlimited will prepare and complete
a habitat restoration plan for Mill Creek. The headwaters of the 21 square-mile Mill Creek
watershed are situated within Cambrian limestone and dolomite geology, creating ideal
conditions for a significant cold water fishery.”[ix]

     Many nature preserves around our country and the world rely on the basic karst
topography to support wildlife.  In addition to our U. S. National Park Service, devoted to
conservation, as mentioned in our March 2005 Mineral-of-the-Month article on calcite, three
such organizations around the world stand out to me as fine examples.  They are: The
Missouri Department of Conservation (for education), the Botsalano Game Reserve in
South Africa (for conservation), and the U. S. Fish & Wildlife Service (for it’s endangered
species programs).

     David Bruns, Conservation Education Consultant in his News from Rockwood Reservation
newsletter article, “We Have Karst”, promotes his state by offering that “[s]edimentary rocks
including limestone and dolomite dominate the geology of Missouri.”[x]

     Missouri cave and karst info: http://www.conservation.state.mo.us/conmag/2000/03/1.htm.

     The Botsalano Game Reserve, formerly a cattle ranch, “[l]ying on the eastern edge of the
Kalahari, the area consists mainly of acacia and karee woodlands and extensive grasslands
dotted with olea clumps which like the dolomite geology.”[xi]

     Our U. S. Fish & Wildlife Service touts that “[t]he Ozarks region of northern Arkansas,
northeastern Oklahoma, and southern Missouri is known for its brilliant autumn foliage,
forested slopes, whitewater streams, icy cold springs, and caves. Springs, sinkholes, and
caves are just a few examples of the types of karst features commonly found in the limestone
and dolomite geology of this region. The term karst is derived from Krs, a place in Slovenia
known for limestone geology (Elliott 2000). In the 17th century, eyeless white salamanders
occasionally washed up out of caves in that region, and inhabitants believed they were the
young of dragons that lived in the earth (Culver et al. 2000).”[xii]  The notion of draconic
troglodytes is intriguing, eh?

Dolostone Geology

     “Sea water, high in magnesium, flows through porous limestone and replaces some of the
calcium with magnesium turning limestone into dolostone.”[xvi]   Therefore, some marine fossils
may be found, especially in the grayer materials around the Great Lakes area.

     “Limestone is composed of material derived by both chemical and biological activities. The
particles of sediment that make up a typical limestone are frequently recognizable as fossil
fragments. By contrast, most dolostone is crystalline.  Dolostone forms when magnesium in
pore water is substituted for some of the calcium in the original limestone, or by direct
precipitation. Most limestones of commercial importance accumulated in relatively shallow
marine environments and are widely available for utilization. Carbonate rocks form about 15
percent of the earth's sedimentary strata.”[xvii]

Pennsylvania Dolomite Geology

   The Pennsylvania Trail of Geology publication series, offered by the Pennsylvania
Department of Conservation and Natural Resources (DCNR), in Park Guide 15 guides you
on a tour of Caledonia and Pine Grove Furnace State Parks.  On a hike you could witness
dolomite geology.

     “The carbonate rock present in some of the low hillsides and valleys of South Mountain is
called the Tomstown Dolomite.  This rock unit is primarily gray dolomite containing interbeds
of white limestone.”  Also, “it has a very low resistance to weathering and thus usually results
in valleys.  Iron ore found at the base of this unit was actively mined in the nineteenth
century.”[xviii]

     If you are heavy into topography and stratigraphy, you might enjoy allusion to more of
Pennsylvania’s geology.

     “Calcite and dolomite occur in the freshwater limestones of the Allegheny, Conemaugh,
Monongahela, and Dunkard Groups. Additionally, in the Monongahela and Dunkard Groups,
calcite and dolomite are the most common carbonate minerals present in other rock types.”

     “Chemical composition data for the Vanport limestone and other Pennsylvanian limestones
and dolomites are shown in Table 8.7. Data from a few Cambrian and Ordovician limestones
and dolomites, including the Valentine limestone from Centre County are included for
comparison, as these high-calcium limestones are well known for their purity and industrial significance…”[xix]

     This is just a taste of the information online, and in books, libraries, and academic papers. 
The DCNR offers many free online publications to learn more of this partially-karsted state.

     Our local dolomite in southeastern Pennsylvania is interspersed with limestone.  All of the
calcium and carbonate families are represented here, including calcite, dolomite, siderite (Mn),
and ankerite (Fe).  Within these ranges over several area quarries, the rock material can be easy to
work for freeing crystals from their vugs, or hellacious.  For the quality of the dolomite crystals
located within, the work is well worth it. 

    Our club’s fieldtrips have rewarded us with magnificent crystals.  Some of the best are pink
saddles nestled in clear calcite and purple fluorite.  An example is from the Kurtz Quarry in
Denver, Pennsylvania.

     Other associated minerals, such as pyrite, chalcopyrite, fluorite, dolomite form massively,
or as crystals, within our area’s limestone and dolostone quarries.  It also occurs with apatite,
barite, gypsum, quartz, and sphalerite.  This author has found some good micromount red
sphalerite and clear quartz crystals in mini-vugs of the Franklin dolostone at the Buckwheat
Dump of the Franklin Mineral Museum, Franklin, New Jersey.

     In Sussex County, New Jersey, it occurs with 358 zinc ore-related minerals, most notably,
near the Franklin Zinc Ore body of franklinite, willemite, and zincite.[xx]

     Beyond our club’s general collecting range lies numerous locales that popularize this vuggy
mineral.  One of our March Show vendors, Isaias Casanova of IC Minerals, has generously lent
some of his dolomite collection photos for us to enjoy.

     To see more Binkley-Ober Quarry Field Trip dolomite vug pictures, visit our field trip pages.

Lapidary

     Michigan Kona Dolomite cabbing rough, slabs, or tumbling rough comes from Kona Hills
South of Marquette, Marquette County, Michigan.  This pink and red, crystalline rock is a major
source for lapidaries.  Two other popular uses for ‘Kona’ are spheres that resemble petrified wood,
and as gemstone handles for art knives.

     Mexican picture dolomite resemble banded agate, whereas, Wisconsin druzy dolomite looks
like reddish-gray quartzite, but softer, of course.  Mottled tan, pink, and purple makes up Forest
County, Wisconsin dolomite rough.

     The countries of Switzerland, Germany, Italy, Morocco, and Spain produce some nice material.

Until Next Time

     If you feel like trekking home before our next installment and field trip to Herkimer, New York,
please do.  We will meet back here on May 1, 2005.  For those of you who want to keep digging,
go right ahead.  There are many resources to explore on this page and links to many others.  By
the time you have explored them all, it will be time to convene for our Herkimer Diamond jaunt.

     Until then, stay safe, and happy collecting.

Links

The Niagara Peninsula Geological Society  (Newsletter is called The Pink Dolomite Saddle)

Niagara Falls State Park, Niagara Falls, New York

Thorold Quarry, Ontario, Canada (pink dolomite saddles)

Article Contributors

Isaias Casanova, IC Minerals

United States Department of the Interior, Bureau of Land Management,
National Park Service  (NPS Photo)

Photo & Graphics Credits

I would like to gratefully acknowledge the generous contributions of our fellow calcite
enthusiasts, collectors, authors, curators, professionals, and club members who made this
work possible.  Thanks.

Isaias Casanova, IC Minerals

United States Department of the Interior, Bureau of Land Management,
National Park Service  (NPS Photo)

Stan Celestian, Glendale Community College, Glendale, Arizona

Susan Celestian, Curator, Arizona Mining and Mineral Museum, Phoenix, Arizona

Niagara Falls State Park, Niagara Falls, New York