An Exploration of the Elberton Granite Quarry Process and
Stone Industry
Scott E. Brame
Geological Sciences
Clemson University
Clemson, SC 29634
Introduction
The exploitation of the Elberton Granite deposit in northeastern Georgia is a story of
American entrepreneurship, a story of individuals who struggled to make the quarrying
process profitable, and of others who started small stone finishing operations in their
backyard that grew into significant businesses employing dozens. Currently, there are
more than 40 quarries in operation and 150 stone finishing plants, with annual granite
industry sales of $170 million. The 2300 granite industry employees have a payroll of
$57 million per year. Understandably, Elberton calls itself the “Granite Capitol of the
World”.
The key to the success of the stone industry and popularity of the Elberton granite is
its mineralogical homogeneity and fine- to medium-grained texture. This combination
makes the granite ideal for stone cutting. The deposit is extensive. The granite batholith
is approximately 35 miles long, six miles wide and most likely two to three miles deep,
and is spread over five Georgia counties: Elbert, Oglethorpe, Wilkes, Greene and
Madison.
This trip will visit several quarries and examine the strategies implemented at each.
The particular geologic setting of each quarry and the techniques utilized at each will
give an understanding of the challenges and opportunities of quarrying in the Elberton
area. A tour of a stone finishing plant in Elberton that employs some of the latest stone
cutting technologies will show the other side of the Elberton granite industry story.
Geologic Setting
The Elberton granite intrusion is located on the eastern edge of the Inner Piedmont,
where the Inner Piedmont meets the Charlotte Belt. The deposit is situated between the
Middleton-Lowndesville shear zone to the east, and the Hartwell extension of the
Towaliga fault zone to the west (Figure 1).
The rocks of the Inner Piedmont into which the granite intruded are complexly
deformed gneisses and schists. Their aluminous character suggests that they are
metasedimentary and metavolcanic rocks, with ages of late Precambrian to early
Proterozoic. Most likely, these rocks started as a series of aluminous sediments
composed of pyroclastic debris, volcanic flows, and terriginous sediments deposited in a
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basin near continental sources. The peak metamorphism of these rocks occurred around
400 m.y. ago, creating sillimanite-grade rocks.
Figure 1. Location and extent of Elberton granite deposit (modified from
Stormer and Whitney, 1980)
The Elberton granite intrusion occurred about 320 to 350 m.y. ago at a depth of 1215 km, and cooled slowly. The homogenous fine-grained texture of the granite has been
explained by a model that proposes the magma intruded upwards until it became vapor
saturated, and then solidified in response to decreasing confining pressure (Stormer and
Whitney, 1980). No internal contacts within the body have been detected, thus it appears
that the pluton is the result of a single intrusive event (Dallmeyer and Swanson, 1999).
The Elberton granite is considered to be post-metamorphic, meaning that the
metamorphic fabrics in the Inner Piedmont had already formed and the area had begun
cooling by the time the intrusion was emplaced. Within the granite, there is no
metamorphic fabric nor other evidence of metamorphism.
Uplift has occurred along faults bordering the intrusion, bringing the batholith to the
surface. The granite body is elongated in a northeast-southwest direction following
regional structural trends, but it is locally highly discordant with abundant dikes. A large
diabase dike can be observed at the Keystone Quarry (Figure 2).
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Diabase dike
Figure 2. Diabase dike (dark colored) cutting the Elberton granite at the
Keystone Quarry, Oglethorpe County, Georgia.
Petrology and Geochemistry
The Elberton granite is a fine- to medium-grained, homogenous, light grey (and
locally light pink) granite. It is composed of approximately equal amounts of quartz,
oligoclase, and microcline, with biotite the other significant primary mineral with
abundances of 4-7%. Accessory minerals include sphene, zircon, allanite, magnetite, and
ilmenite-hematite. Muscovite and chlorite are locally abundant, but are most likely the
result of secondary alteration.
The most striking geochemical feature is the extreme homogeneity of the major
elements. In contrast, the trace elements are highly variable and show a clear regional
pattern (Figure 3). These patterns probably represent heterogeneities that developed
during a partial melting episode in the source region and were preserved by laminar flow
during emplacement of the pluton (Hess, 1979).
Within the granite, there is a poorly defined foliation, mainly in the alignment of the
biotite. The foliation is variable in direction and difficult to define, except near the
contact with the country rocks where it generally parallels the contact. The foliation is
interpreted as being a flow foliation related to the intrusion (Stormer and Whitney, 1980).
The granite industry recognizes three colors in the Elberton granite: blue, grey, and
pink. The blue to gray color can be most likely attributed to fine-grained magnetite. In
some locations where the pink variety of the granite occurs, the mineralogy is identical to
the grey except that the fine-grained oxide is hematite, instead of magnetite. Hess (1979)
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stated that the pink variety found at the Dawn Grey and Sunset Pink Quarries was due to
the presence of very fine scale inclusions of hematite in feldspar, presumably as a result
of slightly more oxidizing conditions in this part of the granite.
Pegmatitic and apilitic rocks occur as irregular magmatic segregations and as late
stage crosscutting fracture fillings. The mineralogy of these bodies is generally similar to
the granite (Stormer and Whitney, 1980).
Figure 3. Regional variation of trace elements in the Elberton granite.
History and Economic Importance
In 1889, Dr. Nathaniel Long opened the area's first commercial quarry and
manufacturing plant, and with railroads providing passenger and freight service to the
area, Elberton began to grow tremendously around the granite industry.
By 1920, there were three or four rock finishing sheds in Elberton, and this grew until
today there are more than 150 companies that turn rough granite into completely finished
memorials or other commercial stone products. Some of those plants are owned by firms
that own and operate quarries; the remaining manufacturing firms purchase their granite
blocks directly from the various quarries in the Elberton area
Monuments are the dominant commodity, accounting for 90 percent of the
production. Elberton currently is responsible for more than one-third of all monumental
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granite produced annually in the United States. In the past three decades, sales of granite
have more than doubled. Currently, sales total more than $170 million annually.
Presently, 45 granite quarries are in operation within a 25-mile radius of Elberton.
More than half of these have been producing stone for monuments for more than 30
years, and some have been quarried to depths as much as 150 feet. Approximately 2
million feet of select blue-gray granite is quarried annually.
In addition, 70 service establishments in the area supply tools and equipment, perform
designing or drafting services, and provide transportation services for local quarries and
manufacturers, as well as for wholesale and retail markets outside of Elberton. In all, a
total of 280 separate companies are operating businesses in granite production or its
allied services. The Elberton Granite Association estimates that those businesses employ
about 40 percent of the non-farming population of the region.
Quarrying Considerations
The goal of quarrying is to break granite into blocks that can be moved to the
finishing plant. While the granite is fairly homogenous, differences in the material
properties have created stress planes within the granite.
There are three planes of weakness along which blocks may be split. The primary
direction of weakness in the Elberton granite is the horizontal plane, called the rift. The
other two planes are vertical, with the run being the secondary plane of weakness, and the
headgrain, or “the hardway”, being the most difficult to separate.
The reasons for these differences are due to a combination of factors: tectonic stress,
magmatic flow direction, mineral fabric, and possibly the alignment of microscopic gas
bubbles (Tom Evans, personal communication). The rift is the primary weakness plane
due to the relief in stress caused by the removal of 12-15 km of overburden.
Given a block of granite, the rift, run, and headgrain can usually be detected by the
roughness. When running your hand over the faces on a block, the rift is smooth to the
touch compared to the run and headgrain. Differentiating between the run and the
headgrain is more difficult, but a practiced hand will detect that the headgrain is slightly
rougher than the run.
Quarrying Methods
There are several methods of freeing large granite blocks. The method used is
determined by the resources of the owner and the experience of the quarry foreman.
Increasingly, the use of automated methods will determine the long-term viability of the
quarry.
Granite quarrying begins by cutting channels on all sides of a large, rectangular
section of granite. Once the ends and backs of a section are channeled (using one of the
methods explained below), horizontal lift holes are drilled along the bottom of the open
face. The holes are loaded with explosive, and the resulting blast has just enough energy
to break the quarry block from the bed of the quarry (along the rift).
After freeing the large rectangular piece, the granite is cut into smaller blocks. To
create the smaller blocks, jackhammers are used to drill horizontal holes about 6-in. apart
along the length of the block, and then steel wedges and shims are inserted in the holes.
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The wedges are hit with sledghammers along the long dimension until the granite is split
by the a fracture linking the stressed wedge points. This section is then cross-cut by
further drilling and wedging into individual blocks, usually 3 to 4 feet wide, 3 to 4 feet
high, and 10 to 12 feet long, weighing 9 to 10 tons. The dimensioned blocks are removed
by derrick or mobile crane and shipped to monument plants for processing.
The channeling methods are explained below. In some cases, combinations of these
methods are used, and/or the process is automated.
Channel Bars
This was the original method of separating blocks, and is no longer used. In this
technique, closely spaced holes (1-2 inches apart) were drilled, and then the space
between the holes was broken apart using a broaching tool. This was a time consuming
method because of the number of holes that had to be drilled, and because the broaching
was slow and inconsistent.
Jet Burner
This tool consists of a long steel pipe with an attached jet burner which burns a
pressurized mixture of fuel oil and air. The jet burner produces a flame with a velocity
about five times the speed of sound, or 4,000 feet per second, and burns at 2,800 degrees
Fahrenheit. The flame causes the granite to disintegrate or break into small flakes and
dust as the heat thermally fractures the granite. The burner cuts a 4-in. wide channel as
the flame nozzle is moved up and down. Using the burner, it is possible to cut a vertical
channel 12 to 15 feet deep at a rate of about 14 square feet per hour. Given that this tool
is in effect a miniature jet engine, it produces a very loud sound.
Drilling and Blasting
A high-speed track drill sinks rows of holes 4” to 6” apart in which Primacord or black
powder explosives are strategically placed and detonated to split the sections loose. The
high-speed drill bits penetrate the granite at a rate of up to 3 feet per minute and can
travel up to 9 feet deep.
Hydrojetting
An extremely high pressure (~30,000 psi) nozzle is attached to a rod steel. This method
produces a surface that is reminiscent of solution channels in limestone. The high rate of
water jetting produces an extremely loud sound, about as loud as the jet burner.
Diamond Wire
This technique consists of an engine pulling wire cable through a system of pulleys and
return wheels. The wire is a steel cable on which diamond-grit-impregnated beads are
held in place by plastic spacers. The wire is threaded through precut intersecting vertical
and horizontal holes in the granite, and then the wire is jointed together making a large
loop which simultaneously cuts the top, bottom, and one end of the granite mass. Water
is used to cool the wire as it cuts. The cut face produced by this process is much smoother
than any of the other processes. If there two open sides, the wire saw can free an entire
block. However, if there is an attached side (to the granite mass), then that side must be
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channeled with a burner, or drilled and blasted free. This method will cut 35 to 40 square
feet of granite per hour, or four to five times faster than a jet burner.
Requirements for monumental granite are exacting, and only about 50 percent of the
granite removed from the quarries finds its way into finished monuments. The remainder
is consigned to commercial applications such as street curbing and gravel, or is discarded
in waste piles.
Finishing Techniques
Blocks are delivered to finishing plants, usually via tractor trailer, where large
circular diamond saws, some with blades up to 14 feet in diameter, cut the blocks into
slabs. Commonly, the slabs, measuring 8 to 10 feet in length and 6 to 8 inches in
thickness, are fed into machines that break the granite slabs into sizes needed for
monuments and markers.
Computer-controlled diamond wire saws offer flexibility in shaping the granite and
are sometimes used to cut the slabs into unusual shapes. Large polishing mills use a
variety of grinding and buffing pads and abrasives that are applied systematically to
create a mirror-like finish. Stone crafters use hammers, razor-sharp carbide tipped
chisels, pneumatic tools, and sandblasting equipment to further carve, shape and define
each individual monument.
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Field Trip Stops
From Clemson, it is about 60 miles to Elberton, Georgia. The field trip log starts in the
parking lot behind the Elberton Chamber of Commerce/Civic Center. The Civic Center
is located 0.8 miles west on College Avenue (Hwy 72/17) of the intersection of Georgia
Highways 77,17, and 72 (main intersection just to the north of downtown district).
Figure 4. Map of stops for the Field Trip.
In Figure 4, the field trip stops are shown, as well as the other quarry locations in the
area. Note that the quarries tend to be clustered in certain areas. This is probably related
to the proximity of the granite to the surface and to the amount of overburden that must
be removed to access the workable stone.
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NOTE: All of the quarries visited during this trip are accessible only by permission
of the owner, and require the signing of a liability waiver. Current Mine Health and
Safety Administration (MSHA) regulations require special training before entering
a quarry in operation.
Road Log
0.0
Elberton Georgia Civic Center. From the parking lot, turn right onto College
Avenue(GA Hwy 72/17) and head west.
0.7
Veer right at the intersection of GA Hwy 72 and 17 onto Hwy 72 (towards
Athens).
3.7
Turn right on Pyramid Road. This road quickly turns to dirt and is not well
maintained.
3.9
Turn right into entrance to the Oglesby Quarry.
Stop One: Oglesby Quarry
Started in 1893, this is the oldest, and longest, continuously operated quarry until
it was closed in the late 1960s. The cover of this field guide shows a photograph of
the mine in its early days. It was reopened briefly in the mid 1980s for a year, and
also from the early 1990s to 2001. The main reason operations were ceased at this
quarry was because an increase in iron content in the form of pyrite was encountered
at depth. Pyrite oxidizes when exposed, staining the blocks a rust color and making
them unsuitable for monuments. This phenomena can be observed on some of the
blocks sitting around the edge of the pit.
At this quarry, many of the different methods for channeling large block sections
can be observed. This includes the use of channel bars, drill and blast, and jet
burning. The relatively smooth sections were created using a jet burner.
This mine was quarried for the “blue” variety of granite, which is found
predominately in the northern end of the batholith. One of the main limitations of
quarrying in this area is that the intrusion is close to the contact with the country rock.
Looking southward from the parking area, the contact with the country rock can be
observed on the west side of the quarry (Figure 5). This proximity to the country
rock made it difficult for the quarry to expand.
From this quarry, head back up Pyramid Road towards Hwy 17.
4.0
Pyramid Quarry can be observed on the right side of the road.
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Country Rock
Figure 5. Granite in contact (approximated by white line) with darker colored
country rock at Oglesby Quarry.
Stop Two: Pyramid Quarry
Immediately adjacent to the Oglesby is Pyramid Quarry. These quarries are
located on the western edge of the batholith. In this location, the contact with the
country rock is irregular, and both quarries are exploiting a relatively narrow
section of the intrusion. Due to the narrowness of the intrusion and the decision
by the previous owner not to expand, the Pyramid became an extremely deep
quarry (>100 feet deep) Eventually, this decision by the previous owner (and
possibly other factors) caused him to declare bankruptcy and sell the quarry. The
subsequent owners negotiated to buy an adjacent property upon which to expand
the operation (Figure 6).
Usually, granite in close proximity to the country rock is finer-grained due to
a faster cooling environment than granite found in the interior of the body, and the
finer-grained textured rock is typically easier to work. This may explain why
these quarries are located in what appears to be a diminishing resource.
In February, 2003, the jet burner technique was being used in this operation to
cut the vertical channels needed to free the large granite sections. The quarrying
process here can be readily observed from Pyramid Road.
From here, head back to Hwy 72.
4.1
Turn left on Hwy 72.
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5.5
Turn left on Crystal Road.
6.3
Entrance to Blue Steel Quarry.
Approximate Scale
15 feet
Figure 6. Pyramid Quarry currently being expanded to the south.
Stop Three: Blue Steel Quarry (formerly called the Veal Quarry)
Caution: This is an extremely dangerous quarry as there are no handrails or
safety fences. Please exercise the utmost caution.
As at the Oglseby and Pyramid, the granite here is of the blue variety, which
is best appreciated when it is highly polished. This quarry contains outstanding
exposures of numerous and varied types of xenoliths composed of biotite schists
and amphibolites (Figure 7). While the xenoliths are geologically interesting,
they make quarrying more difficult, particularly if you are using the burner
technique. There are numerous examples of channel cuts here interrupted where
they encountered a xenolith.
During channeling with a jet burner, the intense heat causes the granite to
expand and flake off. The xenoliths do not react the same way due to their high
mica content When heated, the micas in the xenoliths expand and slide along
their cleavage planes instead of breaking. As a result, channeling through the
xenoliths is laborious, requiring a combination of heating and working the rock
with a tool. This is an inefficient way to quarry, and alternate channeling methods
should probably have been employed here.
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Figure 7. Xenolith (~3 feet wide) in granite at Blue Steel Quarry. This wall was
quarried using the channel bar method.
Not only do the xenoliths make channeling difficult, they can also cause an
entire block of stone to be unacceptable for monument use if the block contains a
large xenolith. This situation, and the possibility that release fractures (can be
observed on the north wall) made block removal difficult, are the most likely
reasons why the quarry is currently inactive.
An examination of the xenoliths reveals a bit of tectonic history. Within the
xenoliths, pegamatite dikes can be observed that terminate at the contact with the
granite, inferring dike development before inclusion within the granite. In
contrast, multiple phases of pegmatite and aplite dikes occurred after the granite
was emplaced and are illustrated by crosscutting relationships (Figure 8).
Where magmas come in contact with country rock, there also exists the
possibility of isotopic “contamination” or exchange effects. Oxygen isotope
studies conducted at this site have shown that the granite adjacent to the xenoliths
do not exhibit any measurable isotopic gradients (Stormer and Whitney, 1980).
This observation is consistent with other studies that show that only minimal
isotopic exchange effects occur where the country rock is highly metamorphosed,
as it is here.
Retrace your way back to Hwy 72.
7.1
Turn left on Hwy 72.
9.4
Turn left into Elberton Granite Museum.
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Figure 8. Cross cutting dike development after granite emplacement. at the Blue
Steel quarry.
Stop Four: Granite Museum and Finishing Plant Tour
Plant Tour of the Eagle Granite Company.
The road log for the rest of the trip will restart at the Granite Museum.
0.0
Granite Museum, turn right onto Hwy 72/17.
0.7
Veer right at the intersection of GA Hwy 72/17 onto Hwy 72 (towards Athens).
3.8
Turn right into the Sweet City Quarry.
Stop Five: Sweet City Quarry
This quarry is exploiting the same narrow part of the intrusive body as being
quarried at the Pyramid and the Oglesby. The influence of the close contact with
the country rock is readily apparent in the orientation of this quarry, which is
basically north to south. The country rock can be seen to the west of the pit.
Hydrojetting was being used to create channels at this quarry in February,
2003. Examination of the quarried blocks will show the side cut by the hydrojet.
In general and where possible, the headgrain (or hard way) plane is cut with the
channeling tool, as this is the most difficult to break with the splitting tools.
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From this quarry, turn right back onto Hwy 72 and head west.
12.4
Turn left on Lexington Road (there is an abandoned stone store immediately on
the right at this intersection).
15.1
Veer left onto N. Eades Road.
15.9
Veer right onto Benton Road.
16.2
Veer left into the Keystone Quarry entrance road.
Stop Six: Keystone Quarry (Oglethorpe County)
Two different blue varieties of granite come from this large active quarry. One is
marketed as “Keystone Blue”, and the other is darker and fine-grained, and called
“Topaz Blue”. These two varieties are separated by a distinct quartz-filled dike that
cuts across the large pit, with the Topaz variety on the back wall.
A large diabase dike more than 30 feet wide is easily viewed from the west side of
the pit (shown previously in Figure 2). While diabase is used as a monument stone,
this particular dike is not quarried as regular blocks cannot be obtained from it, and
the irregular nature of the diabase makes it unsuitable for monuments.
The Keystone Quarry is notable for its use of automation, expanding operations,
and lack of any contact with country rock. In addition to the main large pit, another
pit has been started to the south. In February 2003, an automated jet burner on a track
was observed cutting stone at the new hole to the south with no attendant workers on
site (Figure 9.) The tool cuts a vertical channel at a constant, predetermined rate. At
the bottom of the channel it is retracted and automatically advanced an optimal
distance forward on the track, and cutting is resumed. The tool shuts off when it
reaches the end of the cut. The benefits of this automation are twofold: work
continues around the clock, and the operator is removed from the heat and noise.
There are other automated systems at this quarry. Standing on the west side of the
main pit, a large smooth face can be observed at the top of the far (east) wall. This
smooth face was cut with a 100 foot long diamond saw. The sawing was done with
an automated machine on a track that operated around the clock. The quarry
superintendent, Bobby Harrison, stated that this process took three weeks, which was
four times faster than using a burner. Most of the other cuts in the main pit were done
using burners.
Up on the hill behind the main pit is another automated system: diamond saws
cutting blocks to be used as curbing in New England (Figure 10). The saws cut slabs
of three different thicknesses: 11 in., 15 in., and 17 inches. The slabs are carried by
truck to the rail yard in Elberton and shipped to Boston where they are cut into
curbing material. In New England, the constant use of salt on icy and snowy roads
corrodes concrete curbs and makes it economical to use granite curbing. This is an
excellent use of blocks that have been rejected for the more profitable monument
trade. The saws are automatically advanced, only removing about ¼’’ of stone per
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pass. This investment in automation indicates that the Keystone owner is responding
to an increasingly competitive stone market.
Figure 9. Automated jet burner on a track at new pit, Keystone Quarry
Figure 10. Diamond saws cutting curbing onsite at Keystone Quarry.
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Biography of Tom Evans, Sr.
Studied geology at the University of Tennessee at Chattanooga and the University of
Tennessee at Knoxville. For the past 40 years he has been involved in the planning,
development, management, and acquisition of dimension stone quarries as a consultant
and as a quarry owner. In 1975, he established the Evanswinn Company with a partner.
Evanswinn exports granite from North America to Europe, Japan, and Korea, and imports
granite from Zimbabwe, South America, and Brazil.
Acknowledgements
The assistance of several individuals was critical for the success of this trip.
Tom Evans was invaluable, and without his help, this trip would just not have
happened. In the Elberton stone industry, he knows everybody and they know him. Just
mentioning his name opens doors in the Elberton area, and other places I am sure.
Thanks to Tom Robinson of the Elberton Granite Association for arranging the plant
tour, Peggy Childs for allowing us to visit the Blue Steel Quarry, Tom Oglesby and
Bobby Harrison for allowing us to visit the Keystone Quarry, Willie Simmons and sons
Bill and Mike Simmons of the Sweet City Quarry, and Eagle Granite Company for
allowing us to view the granite finishing and monument process.
References
Dallmeyer, R. David, and Samuel E. Swanson, 1999, Geology of the Elberton Granite
and Stone Cutting Industry of Northeastern Georgia, in Geological Society of America,
Southeastern Section Meeting, Compendium of Selected Field Guides, March 24-26,
1999
Elberton Granite Association, P. O. Box 640, Elberton, Georgia
Hess, Jim, 1979, Geochemistry of the Elberton Granite and Geology of the Elberton West
Quadrangle, Georgia, M.S. thesis, Univ. of Georgia, Athens, GA.
Stormer, John C., Jr. and James A. Whitney, 1980, Geological, geochemical, and
geophysical Studies of the Elberton Batholith, Eastern Georgia, A Guidebook to
Accompany the 15th Annual Georgia Geological Society Field Trip, Georgia DNR
Guidebook 19
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