UNC Charlotte Department of
Geography and Earth Sciences
Building Stone Walking Tour
of Uptown Charlotte
John Diemer (jadiemer@uncc.edu), Martha Cary Eppes
(meppes@uncc.edu), John Bender (jfbender@uncc.edu,
Emily Henke, Jennifer Aldred, Seth Brazell, Brian Biggers, and
Suzanne Jones; University of North Carolina at Charlotte
Charlotte, North Carolina is the largest city in the Carolinas (population
~750,000, 1.7 million in the metropolitan area) and is one of the
major banking and investment centers of the world. The city dates
to the late 18th century and has gone through multiple episodes of
urban renewal throughout its history. Charlotte was the location of a
gold-rush in the early 19th century and was subsequently the location
of the first United States Mint located outside of Philadelphia. Today
the “uptown” area of Charlotte is dominated by 20th and 21st century
glass and steel skyscrapers; the 60 story Bank of America building is
the tallest building between Philadelphia and Atlanta. In the process
of more than two centuries of urban development, building stones
have taken on an important role in construction of everything from
pavers, curb stones, and street level planters, to building cladding,
and floors and walls of building lobbies. Historic buildings, principally
churches, have survived the redevelopment of uptown, and they also
contain significant building stones as foundations, stairways, lintels
and other architectural elements.
Here we present a sampling of the wide variety of building stones
readily visible in uptown Charlotte construction. The guide is the
product of the collective effort of graduate students, undergraduate
students, alumni and faculty from the Department of Geography and
Earth Sciences at the University of North Carolina at Charlotte. In
this guide, we attempt to describe each building, including its history,
the building stones used in its construction, their specific geologic
information, and whenever possible, the provenance of the origins
of the visible building stones. We attempted to include information
at each stop that would appeal to the expert, but also inform the
novice. The tour begins at the College Street entrance of the Charlotte
Convention Center and winds its way north along Tryon Street to 7th
Avenue. There the tour heads east to the light rail line and makes its
way back south toward the Convention Center. Although definitions
of terms are generally given in that order, the guide is designed to be
accessible at any of the locations. Enjoy your tour of Uptown Charlotte
and its various types of Building Stones!
An electronic version of this guide is available as a PDF on the GSA website
(www.geosociety.org) or as a Google Map at http://goo.gl/maps/xb96
UPTOWN ROCKS: a walking tour of Charlotte City Center
Annual Meeting of the Geological Society of America
Building
Stone
Walking
Tour of Uptown Charlotte
Charlotte, North Carolina;
November
2012
7th street
Q
P
LEVINE
7TH STREET STATION
DISCOVERY
PLACE
6th street
O
HEARST
N
5th street
ARENA
MAIN
BOA
R
M
S
trade street
ARENA STATION
L
INTERSTATE
CTC
LEGEND
Visually Stunning Rocks
K
EPICENTER
SUNTRUST
Sedimentary Rock
4th street
Metamorphic Rock
J
Igneous Rock
BB&T
More than one type
3rd street
Building
G
F
2nd street/MLK
H
E
1 WELLS FARGO
A
CONVENTION
NASCAR
O
RT
H
CENTER
N
ENERGY
college street
DUKE D
B
Lynx Light Rail
I 3WF
1st
C
Overstreet Mall
STATION
THE GREEN
tryon street
church street
BOA#2
HILTON
brevard street
LATTA
T
3RD STREET
caldwell street
2WF
STONEWALL
STREET STATION
500 ft
200 m
page 2
Stop A: The Green
College Street and 2nd Street
The 1.5 acre urban pocket park known as the Green is located
between the 400 block of South Tryon and South College Streets,
immediately west of the Charlotte Convention Center. Designed by
Wagner Murray Architects of Charlotte, it was completed in 2002
and sits directly on top of a 7-level underground parking structure.
fig3
This fine-grained quartz sandstone was quarried near Crossville,
Tennessee. Red iron staining highlights cross-bedding on some
specimens. The high quartz content in this sandstone, deposited
along the coast of an inland sea that covered most of North America
in the Mississippian, about 340 million years ago, has made it
a desirable and durable building stone. It is called a fieldstone
because it has been left in its natural state.
A2: Sandstone capping retaining walls
This fine-grained, plane-bedded sandstone, used throughout the
Green as retaining wall caps, was also quarried near Crossville, TN.
One of the capstones on the southern side of the plaza has ripple
marks (Figure 3), others have parting lineation (the small ridges
evident on bedding planes where the stone has split). This stone
was likely formed in a deltaic setting associated with the inland sea
mentioned for A1 above, as evidenced by its plant fossils (Figure 4).
Can you find a plant fossil in one of these stones?
Figure 2. Stop A1: Tennessee Fieldstone
Figure 3. Stop A2: Tennessee Bluestone ripple
marks
fig4
fig2
Ratcliffe on the Green
A1: Sandstone blocks in the retaining wall
Figure 1. Stop A: The Green
Figure 4. Stop A2: Tennessee Bluestone
plant fossils
page 3
A3: Upper sections of the pillars on the ‘Ratcliffe on the
Green’ building
This limestone is a packstone (according to the Dunham classification
scheme) meaning it is grain supported and the pores between the
grains are filled with calcareous mud. It has a fine to medium grained
texture (you can see individual grains without magnification), and
contains a type of fossilized shell fragments known as bivalved
molluscs, such as those visible in Figure 5.
Figure 5. Stop A3: Fossiliferous limestone
Many limestones form in warm, shallow seas where organisms with
shells composed of calcite (CaCO3) accumulate layer by layer and
eventually become lithified into a limestone. This example contains
fossilized shell fragments and ooids (small spherical grains). Pull
out your hand lens, because ooids are particles < 2mm in diameter
that form when individual aragonite grains accumulate concentric
layers of carbonate as they roll around on the shallow sea floor.
Can you find the ooids? How many different other fossils can you
observe in this building stone?
A4: Pillar bases on the ‘Ratcliffe on the Green’ building
This light colored packstone is composed of medium to coarsegrained skeletal fragments of shells, peloids and possibly ooids.
The skeletal fragments are best seen on the cut edges of the blocks.
Figure 6. Stop A4: Packstone/limestone
Stop B: St. Peter’s Catholic Church
507 S. Tryon Street, Charlotte, NC 28202
The cornerstone of the original St. Peter’s Catholic Church was laid in 1851 at the corner of Tryon and
First Street. St. Peter’s remained the only Roman Catholic church in Charlotte for the next 90 years. A
munitions explosion at the end of the Civil War damaged the foundation of the original building. The
cornerstone for the current building was laid in 1893. At the time, the church was on the southern
limits of Charlotte, surrounded by empty lots. According to Charles A. Hastings, the architect for the
recent renovation of the church, the structure is of Victorian gothic style, simplified to a Germanic
starkness prevalent in the post-war South. Victorian details such as the basket weave brick panel in
the bell tower, fish scale slate roof, and just a hint of gingerbread on the steeple dormers suggest the
era’s love for repeated design motifs.
B1: Church façade
Can you determine how many different igneous rocks
were used in the façade and adjacent pavement? We
found at least four. These rocks are Silurian and Devonian
aged granites locally derived from the Charlotte Belt,
commonly interpreted as an exotic terrane accreted to
North America during early to middle Paleozoic time.
Can you spot the one piece of marble on the church
property?
Figure 7. Stop B1: Various granites and one marble
page 4
Stop C: Mint Museum Plaza
500 South Tryon Street, Charlotte, NC 28202
Opened on October 1, 2010, the Mint Museum Uptown is a five-story
building designed by Machado and Silvetti Associates of Boston. It
houses the Mint Museum of Craft + Design as well as American,
contemporary, and European art collections.
The plaza in front of the Mint Museum Uptown is covered with
a checkerboard of pavers composed of intrusive igneous rocks
including gabbros and diorites (Figure 8).
Figure 8. Stop C: Mint Museum gabbro and
diorite pavers
C1: Gabbro pavers
The dark-colored gabbro pavers have interstitial pyroxenes and
plagioclase feldspar with bladed laths (Figure 9). The upper platform
also has smaller pavers composed of this rock.
C2: Lighter pavers
The diorite pavers contain xenoliths (pieces of ‘foreign’ rock that
get incorporated into the magma without completely melting) of
at least two different rock types, mostly fine grained basalts and
diabases (Figure 10-11).
Who in your group can stand on the biggest xenolith? We found one
that is 8 cm in length!
Figure 9. Stop C1: Gabbro pavers
Figure 10-11. Stop C2: Diorite pavers with xenoliths
page 5
Stop D: Duke Energy Center and the Harvey
Gantt Center
400 South Tryon Street and 551 S. Tryon Street
Completed in 2010 this 48 floor (764 feet) LEED Gold certified
office building was designed by Thompson, Ventulett, Stainback &
Associates, Jenkins-Peer Architects, and the Frelon Group. Despite
its LEED status, the building stones were quarried from all over the
world.
Completed in 2009, the four level, 46,500-square-foot Gantt Center
was designed by the Frelon Group Architects. It is located in the
area once occupied by the historic Brooklyn neighborhood, a black
community razed in the 1960s. Inspired by the former Myers Street
School, with its prominent exterior staircases, the building’s exterior
utilizes patterns reminiscent of quilt designs from the Underground
Railroad era and woven textile patterns from West Africa.
D1: Duke Energy Building exterior cladding
The meta-granite exterior cladding of this building (Figure 12) was
quarried in Brazil, then cut and polished in San Sebastián, Spain,
before being shipped to North America where it is used commonly
as building stone. Its minerals include: quartz (smokey gray),
orthoclase feldspar (milky white), sodic plagioclase (also white in
color) biotite (black), and muscovite (pale green to golden brown).
The obvious flow fabrics, suggest the rock was subjected to
metamorphism at some time during the long history of deformation
of the South American craton. A granite with two micas such as this
one is relatively rare and speaks to an unusual magmatic history.
D2: “Staturetto White” marble
The light stone in the wall is a white marble (metamorphosed
limestone) with gray veins. This stone was quarried in Carrara, Italy,
as was the marble for Michelangelo’s sculpture of the Pieta in St.
Peters Cathedral in Rome and the David in Florence. The limestone
protolith for the Carrara Marble is Jurassic in age. This parent rock
was metamorphosed to marble during a poorly understood Tertiary
uplift event of the Alpi Apuani mountains, where Carrara is located.
Figure 12. Stop D1: Margherita White
Granite (Brazil)
D3
D2
D5
D4
D6
Figure 13. Stop D2-D6: Marbles, limestones
and igneous rocks in the Duke Energy
Building interior; quarried from Europe,
Africa and Asia.
D3: “Grigio Carnico”
The dark stone in the wall is known as “Grigio Carnico”. It is a common building stone composed of
black limestone with white veins of calcite. Also present are dark stylolites, which form along bedding
planes in limestones and marbles. Styolites form as material on either side of the bedding plane
undergoes compaction and differential solution, which results in the interpenetration of points and
cones forming a rough contact surface. In cross-section, the stylolites appear as jagged, zigzag lines
with considerable relief. The black color is likely due to high organic content. This stone was quarried
in Vicenza, Italy, on the southern flanks of the Alps.
D4: “Black Angola”:
The dark black gabbro floor paver was quarried in Malala, Angola.
D5: “China Impala”:
The medium gray diorite floor paver along the lobby edges was quarried in Fujian, China.
page 6
D6: “White Pearl” granite
The light paver which covers most of the lobby floor and the exterior
entryway is a more typical one-mica (biotite) granite that was
quarried from Madrid, Spain.
D7: Gantt Center courtyard syenite sculpture
Walk across the street from the Duke Energy Center to the Harvey
Gantt Center courtyard. There you will find a nice example of the
contrast in appearance of stone that is “polished” vs. unpolished.
Much like natural weathering, polishing a rock can change its
appearance remarkably. It is hard to believe that the two contrasting
portions of the sculpture are the same rock.
Figure 14. Stop E: Bank of America at 400
South Tryon
D8: Gantt Center courtyard pavers
The lighter colored pavers in the Harvey Gantt Center Courtyard
are a nice example of an almandine garnet-bearing meta-granite.
The garnets are clearly visible as the dark-reddish minerals in the
pavers. Rub your finger over them to feel how they stand in relief
above the more easily weathered matrix of the stone.
The darker gray pavers are the same diorite as stop C2 and the
pinkish tiles and pavers are the same accent stone found throughout
the City and described in stop L4.
Figure 15. Stop E1: Rapakivi granite
Stop E: Bank of America at 400 South Tryon
(formerly Wachovia Center) South Tryon at 2nd Street
Completed in 1974, this 32 floor (420 feet) office building was
designed by Little and Associates in the architectural style known
as modernism (Figure 14).
E1: Exterior pavers
Examine the pavers (trade name often “Baltic Brown”) in front of
the Bank of America Building at the corner of South Tryon and 2nd
Street and you will see a distinctive granite that features round
Figure 16. Stop E2: Travertine
mineral grains known as rapakivi whose formation have puzzled
igneous petrologists for decades (Figure 15). Typical rapakivi
texture is a mixture of variously mantled (that is to say rimmed),
non-mantled or partly mantled, concentrically zoned, plastically
distorted, fragmented, re-aggregated, large and small distinctly round minerals (ovoids). Commonly
the ovoids themselves are orthoclase feldspar which may be mantled by plagioclase. Some ovoids
display remarkable sphericity and are often mis-labeled as orbicular. The compositional and textural
zoning of each ovoid is thought to reflect its history of crystallization related to temperature and
pressure changes within the melt that produced the overall rock. The mantling is thought to occur
during the reduction of pressure accompanying the emplacement of the magma into the country rock.
Who in your group can find the largest ovoid?
E2: Exterior travertine planters, pavers and walls
Travertine is a form of limestone deposited rapidly by spring water with a high mineral content (Figure
16). It often has a fibrous or layered appearance such as those visible here, and it occurs in white, tan
and cream (here) colored varieties. In caves it can form stalactites and stalagmites. It is frequently
used as a decorative building material. Take a close look at all of the voids and small layers visible
in the cut stone and imagine the centuries and millennia of mineral-rich water flowing and bubbling
across the surface making this laminated rock.
page 7
Stop F: Charlotte Information Center
330 South Tryon
F1: Exterior planter cobbles
The river cobbles visible at the entryway to the 330 South Tryon building (Figures 17 & 18) are similar
in size and roundness to typical Piedmont river cobbles. These cobbles are rounded suggesting that
they have traveled a sufficient distance to have their corners smoothed. The composition of the cobbles
suggests that they were eroded from a mafic source rock.
Figure 17. Stop F1: Mafic river cobbles
Figure 18. Stop F1: Mafic river cobbles
The mafic river cobbles at the 330 South Tryon building are similar in size and roundness to Pleistoceneaged quartz cobbles commonly found in terrace deposits of the nearby Catawba and Pee Dee Rivers.
The cobble deposit visible in Figures 19-20 is located at a quarry adjacent to the Pee Dee River in
Lilesville, NC, fifty miles southeast of uptown Charlotte. These major Piedmont rivers are typically
characterized by adjacent terraces that range from a few meters to over a hundred meters in height
above the modern channel and are thought to range in age from about 5000 to 1.5 million years.
Gravels such as these speak to much different flow regimes in the past than those of the sanddominated modern channels of today.
Figure 19. Pee Dee River gravels, Lilesville, NC
Figure 20. Pee Dee River gravels, Lilesville, NC
page 8
Stop G: Two Wells Fargo Plaza
301 South Tryon
The Two Wells Fargo building (Figure 21, formerly known as Wachovia
2) features a large plaza with outdoor seating and multiple water
features. The plaza is often used for outdoor events and is a great
place for a picnic lunch. Look inside the interior lobby for more
examples of marble and travertine.
G1: Exterior cladding; bench walls and capstones surrounding
plaza
Figure 21. Stop G: Two Wells Fargo Plaza
This visually stunning rock tells a story of several major metamorphic
events (Figure 22 & 23). The parent rock was likely a granite that
was subjected to sufficiently intense heat and pressure (amphibolitegrade metamorphism) to cause minerals of different compositions
to segregate into corresponding light and dark bands clearly visible
throughout the rock. This newly formed “gneiss” was then subjected
to even higher temperatures (upper granulite facies) which caused
a high level of partial melting and recrystallization of many minerals
as evidenced by the highly deformed thin bands of fine-grained mafic
minerals and regions of light-colored, mega-crystic plagioclase and
orthoclase grains (light peach and milky white in color). The final
product is a migmatite. As the rock began to cool, a third event
injected molten magma into the migmatite which crystalized into
the light-colored, quartz-rich veins that cross-cut the foliation.
G2: Fountain capstones
The dark stone benches and cladding material at the base of the
Interstate Tower, Two Wells Fargo Plaza, and in other structures
throughout the city, is often referred to as “black granite”. It actually
is a gabbro containing a plagioclase feldspar known as labradorite
which has a “labradoresence” or schiller effect, consisting of
a stunning play of color and blue-green iridescence visible from
certain angles (Figure 24-25). This optical phenomenon is the
result of light refracting within lamellar intergrowths of Na-rich and
Ca-rich lamellae within the crystal structure. The lamellae result
from phase exsolution during cooling. The medium- to coarsegrained minerals visible throughout this rock are plagioclase (grey)
pyroxenes (black) and possibly some olivine (green).
Figure 22-23. Stop G1: Migmatitic gneiss
G3: Plaza pavers
Light colored pavers in the plaza are a locally quarried stone, the
Mount Airy Granite (described in full in stop H1). The medium dark
pavers are a granite similar to those described at stop L4, and the
dark pavers are a gabbro, both intrusive igneous rocks formed from
crystallization of magma deep within the earth’s crust.
Figure 24. Stop G2: Gabbro
Figure 25. Stop G2: Gabbro
page 9
Stop H: Exterior of Three Wells Fargo Center
(formerly Three Wachovia Center, Three First Union Center)
401 South Tryon Street
This 32 floor post modern office building (450 feet) was completed
in 2000. The architects were Thompson, Ventulett, Stainback &
Associates.
H4
H3
H1
H1
H1: Exterior column cladding near building, upper
The light gray, “salt-and-pepper” meta-granite (Figures 26 & 27) is
from Mt. Airy, Surry County, North Carolina, (home of Andy Griffith
and the town after which “Mayberry” was modeled in the well known
TV series). Mississippian in age having been dated at 334 +/- 3 Ma,
this light-colored, biotite granitoid or monzogranite is dominated
by tabular, sodic plagioclase feldspars, many of which have their
long axes parallel to a weak foliation. The Mt. Airy quarry is the
largest open-faced granite quarry in the world, and is one of the few
quarries in the United States that exports granite to China. Mt. Airy
Granite is the official “rock” of North Carolina.
H2
H2
Figure 26. Stop H: Exterior column cladding
H2: Exterior column cladding near building, lower
The pink-colored, coarse grained syenite (Figures 26 & 28) has rare
quartz crystals and is dominated by pink orthoclase feldspar with
some black hornblende amphibole and light colored plagioclase.
The long axes of the orthoclase minerals are roughly oriented in the
same direction indicating the flow of magma during crystallization.
Xenoliths present in the rock appear to follow the same flow pattern.
Syenites are generally formed by alkaline igneous activity, likely
within thick continental crust. To produce a syenite of this type, it
is necessary to partially melt a gabbroic source rock to a relatively
small degree (~5-10%).
H3 and H4: Exterior column cladding granite
Figure 27. Stop H1: Salt and pepper metagranite
Figure 28. Stop H2: Pink syenite
The columns near the street (Figure 26) have two additional, more
“typical” garden variety granites. There is still another one in the
building cladding above the level of the street.
Can you describe the differences?
page 10
Stop I: Interior of Three Wells Fargo Center
(formerly Three Wachovia Center, Three First Union Center)
401 South Tryon Street
I1: Walls (I1 in Figure 29) contain “Calacatta Gold Marble” building
stone from Italy. This is a fine-grained, white to beige marble,
formed from carbonates deposited as part of the Lias group of the
early Jurassic Period (~180 - 200 million years ago).
I2: Flooring (I2 in Figure 29) is composed of “Botachino Fiorito
Marble” building stone. This light beige, magnesian limestone is also
of the Lias group of the Jurassic Period. While this stone is called a
‘marble’ in the US and Chinese markets, in Europe it must be called
a magnesian limestone, according to the “European Standard” of
building stones.
I3: Flooring (I3 in Figure 29) is composed of “Ruoms Limestone”.
This dark, fossiliferous limestone is from Ruoms, a city in southern
France.
I1
I4
I3
I2
I5
Figure 29. Stop I1-I5: Marbles and granite
I4: Flooring (I4 in Figure 29) is composed of a light-gray, coarsegrained granite building stone known as “Luna Pearl” from either
Italy or Brazil.
I5: Flooring (I5 in Figure 29) is composed of dark-colored gabbroic
anorthosite. This stone is known as “Black Galaxy Granite”.
Black Galaxy is quarried near Ongole, Andhra Pradesh, southern
India. The gold specks are due to the presence of magnesiumrich orthopyroxene (“bronzite”). Black Galaxy is one of the more
common stones used throughout the US for countertops in kitchens
and bathrooms.
I6: Flooring on second level.
It is worth the trip up the escalator to view the nice examples of
bisectional coiled ammonoid fossils in carbonate rocks (Figure 30).
It is located in the floor tile just to the right of the top of the up
escalator.
Figure 30. Stop I6: Bisectioned coiled
ammonoid fossil
page 11
Stop J: BB&T Center
(formerly Southern National Center) 200 South College Street
A 22 floor office building (300 feet) finished in 1975 by Little &
Associates architects, this building, with its Overstreet Mall, was
inspired by a Minneapolis design with the intention of fostering
retail shopping. For this reason, the building does not face a major
street, but was intended to be part of an interior network of bridges
between office buildings.
J1: BB&T Overstreet Mall interior floor tiles
Head inside and upstairs into the Overstreet Mall hallway to view
floor tiles that are alternating dark and light colored carbonates
(Figures 31-33). Both are algal laminated (fine layering caused
by the growth of agal mats) and bioturbated (mixing caused by
burrowing organisms). Algal mats grow where sunlight initiates
the growth of blue-green algae in shallow water, for example on
the floor of a tidal flat pond. During storm events thin layers of
carbonate mud can coat the algal mats. After the storm the algal
mat can re-colonize the surface. Where this process is repeated,
multiple layers of algal mats can build up. The bioturbation can be
recognized by the disruption of what would have been relatively
flat, thinly laminated bedding.
J2: BB&T exterior cladding
The black rock that comprises much of the exterior cladding of the
BB&T building along Tryon Street is an anorthositic gabbro containing
calcic plagioclase feldspar, orthopyroxene, clinopyroxene, and a
small amount of amphibole.
Can you recognize the weak alignment of some feldspar crystals
that indicate flowing magma?
Figure 31. Stop J: BB&T Center
Figure 32-33. Stop J1: BB&T Center
Stop K: SunTrust Bank
K3
(formerly First National Bank of Charlotte)
112 South Tryon Street
This 21 floor neoclassical office building (250 feet) was finished in
1926 by architect Louis Asbury Sr.
K1: SunTrust Bank façade for floors 4-22 (look up!)
The cladding for much of the SunTrust Building is an oolitic limestone
quarried by the Bedford Cut Stone Company in Bedford, Indiana. The
limestone is the Salem limestone, which a member of the Sander
Group. The Salem limestone is a part of a limestone belt extending
from Stinesville, in Monroe County, to Bedford, in Lawrence
County, Indiana. The Salem limestone was deposited during the
Middle to Late Mississippian (~335 to 340 Ma) when a shallow,
inland sea covered much of the North American craton. The Salem
limestone is chemically pure (~ 97% calcite) and is classified as a
grainstone. It contains a variety of fossils including foraminifers,
bryozoa, gastropods, crinoids, bivalves and brachiopods. The Salem
limestone is a freestone, meaning it has no preferential direction of
splitting. This allows it to be cut and carved into a variety of shapes
K2
Figure 34. Stop K3: Entrance to the
SunTrust Bank with travertine (K2) and
cross-bedded sandstone (K3)
Figure 35. Stop K2: Travertine
page 12
and sizes, which has made it a desirable building stone across the
US since it was first quarried in 1827.
L1
K2: Façade adjacent to the SunTrust Bank entrance
Adjacent to the SunTrust entrance is travertine (Figures 34 & 35)
similar to that at stops E and O.
K3: SunTrust Bank Lower façade in the entryway
This stone is a cross-bedded sandstone whose layering is
accentuated by reddish oxidation (Figure 34). In some of the
blocks, there is evidence of wavy soft-sediment deformation. Softsediment deformation structures such as those visible here occur
during the very first stages of sediment compaction as it begins its
slow journey to becoming a sedimentary rock. The very wet and
loosely packed sediments deform as they are dewatered, resulting
in unusual patterns in what would have originally been relatively
simple and uniform bedding.
L3
L2
Figure 36. Stop L: Interstate Tower building
stones
If you walk south along Tryon Street from the Sun Trust you might
notice some nice slates and greenish fossiliferous marbles at the
entrance to the 200 S. Tryon building.
Stop L: Interstate Tower
Figure 37. Stop L1: Serpentinite
121 West Trade Street
This 32 floor post-modern office building (462 feet) was finished in
1990 and designed by architects Kohn Pedersen Fox Associates PC
and Odell & Associates.
L1: Serpentinite
Serpentinite is a low-grade metamorphic rock of ultramafic
composition that consists mostly of serpentine, chlorite and talc
(Figure 37). It can vary in color from bright green to nearly black
and is commonly referred to as “green marble” or “serpentine
marble”. Serpentinites are commonly veined with calcite, dolomite,
magnesite or magnesium carbonate which gives the rock its
characteristic “marbled” fabric. The range in color may result from
the variable amounts of forsterite and fayalite (species of olivine)
that were present in the ultramafic parent rock (e.g. peridotite).
L2: Black Granite
The so-called “black granite” at the base of the building (Figure 36)
is another example of the gabbro already described for the Two
Wells Fargo Plaza and the Three Wells Fargo building (Stops G and
H). This gabbro, however, contains less labradorite than others you
may have already seen.
Figure 38. Stop L3: Light gray granite
L3
L1
L4
Figure 39. Stop L4: Red granite
L3: Interstate Tower light gray granite
The light gray granite (Figures 36 & 38) is felsic in nature, a term
that is applied to rocks with high feldspar and silica content. This
particular granite is composed of ~40% orthoclase feldspar (pink),
~35% plagioclase feldspar (white/gray), ~20% quartz (clear) and
~5% biotite and amphibole (black). A granite with co-crystallizing
page 13
feldspars (as evidenced by their euhedral crystal shapes) is relatively
unusual and is likely a result of the melt’s initial composition.
Rapakivi texture (stop I), zoning, and xenoliths of a finer grained
granite are also evident in this rock.
L4: Seating walls in Thomas Polk Park (Figure 39) and the
columns of the four sculptures at the corner of Trade and
Tryon Streets (Figure 40)
The intersection of Trade and Tryon Streets is considered the
official center of the City of Charlotte and hosts four statues by
artist Raymond Kasky titled “Transportation”, “Future”, “Commerce”
and “Industry”. The base of the statues as well as the sculpture
and walls of Thomas Polk Park which is located just in front of the
Interstate Tower, are composed of a red granite with quartz veins
and entrained xenoliths. A high iron content explains the deep red
color. The granite used in this park is similar to that of many of the
sidewalk paving stones and other features you may have noticed
and have been noted throughout the tour. It is the chosen primary
accent stone for the city of Charlotte. This park marks the site of
the first courthouse built by Thomas Polk, the founder of Charlotte.
The Mecklenburg Declaration of Independence was likely read here
on May 20, 1775.
Figure 40. Stop L4: Red granite pillars at
corner of Trade and Tryon Streets
Stop M: Bank of America Corporate Center
100 North Tryon Street
This 60 floor post modern office building (871 feet) finished in 1992
was designed by Cesar Pelli & Associates Architects (Figure 41). No
photos are allowed inside the building for security reasons.
Figure 41. Stop M: Bank of America Tower
M1-M3: Exterior cladding stones
Three Precambrian granites comprise the cladding stones of this
building. The first is from Ortonville, Minnesota (M1 in Figure 42)
and has the trade name of “agate”. The second is derived from
Marble Falls, Texas, (M2 in Figure 42) and goes by the trade name of
“sunset beige”. The final granite (M3 in Figure 42) is from Milbank,
South Dakota and sometimes goes by the name of “carnelian” or
“Dakota Mahogany” (see stop T4 for more information).
M4: Courtyard pavers
The white pavers in the BOA Corporate Center courtyard are a
classic white marble similar to the Carrara marble described in Stop
D. Metamorphic black schist and a gray granite are the other two
pavers.
M5: Exterior columns
The dark columns at the entryway are serpentinite, a metamorphosed
peridotite (see Stop L for a full description).
M1
M2
M3
Figure 42. Stop M1-M3: Bank of America
Tower exterior cladding, three granites
M6: Fountain
The dark rock that forms the fountain is a typical medium- grained
diorite that contains fine-grained xenoliths along with pyroxene,
amphibole and small amounts of quartz.
page 14
M7: Founder’s Hall flooring and walls
It is definitely worth the effort to view to the main lobby of the BOA
Corporate Center as well as Founder’s Hall, an interior shopping
and dining area. The upper level of Founder’s Hall is part of the
overstreet mall.
Can you identify the ~dozen different marbles utilized in the lobby
of the main tower as well as in Founders Hall? These marbles came
from quarries in Spain, Italy, France, Turkey and the United States.
One of the pink colored Italian marbles is Devonian in age and it is
known as “fior de pesco” (peach flower). It is a favorite construction
material of Cesar Pelli, the building’s architect, and is especially
abundant in the main hall.
Also of note, the lobby of the Bank of America Corporate Center
contains one of the largest secular frescoes in the world. The fresco
is the work of artist Ben Long and it took a year to complete.
Figure 43. Stop M7: Founder’s Hall, various
marbles
N3
Stop N: Hearst Tower Interior Lobby
214 North Tryon Street
This 47 story post modern office building (659 feet) was finished
in 2002 and designed by architect: Smallwood, Reynolds, Stewart,
Stewart & Associates, Inc. No photos are allowed inside the
building for security reasons.
Located within the College Street lobby of the Hearst Tower, there
are brass railings from the Au Bon Marche department store in
Paris. These railings accentuate the tower’s art deco influences. The
building lacks a 13th floor for superstitious reasons.
N1-N3: Floors and walls of the interior lobby
The lighter colored floor stone is an augen gneiss (N1 in Figure 44)
with the trade name “spray white” granite. Generally, augen gneiss is
a high-grade metamorphic rock whose parent rock was likely granite.
Augen comes from the German word for “eye”, as the sample’s
main features are lenticular porphyroblasts of white plagioclase
feldspars (1 in Figure 45). Black biotite compresses around these
more resistant white feldspars in a preferred orientation. The augen
gneiss was quarried at Xiamen, China, near Beijing.
The second type of stone in the flooring is “dynasty black” granite.
(N2 in Figure 44) also from Xiamen, China. This granite is a very
common countertop stone, which is actually classified as a gabbro,
an igneous rock with dark minerals.
N2
N1
Figure 44. Stop N1-N3: Hearst Tower
1
1
Figure 45. Stop N1: Augen gneiss
The walls in the lobby are dominated by “Beijing white” marble (N3
in Figure 44) from Yi Sin, China. This marble has distinctive stylolites
(see stop D for a definition of stylolites) which are accentuated by
a coating of insoluble residue. The marble was cut as facing pieces
from the same block. When one of the pieces is rotated and they
are placed side-by-side, they create a “book-end” marble effect.
page 15
Stop O: Hearst Tower courtyard
214 North Tryon Street
O1: Hearst Tower: Exterior cladding and plaza seating wall
lower stone
The black walls flanking the entrance to the Hearst Tower (as well as
accent seating and unpolished pavers throughout the courtyard) are
composed of anorthosite (a plagioclase feldspar-dominated igneous
intrusive rock) with variable plagioclase crystal sizes belonging
to the Cambrian Lac-Saint-Jean anorthosite suite from Quebec,
Canada. This stone (Figure 48) has the trade name of “Peirbonka
granite”. In certain light, the phenocrysts (large crystals) in this
rock have a lovely blue iridescence.
O1
O1
O2: Entry way pavers
The lighter colored pavers in the Hearst Tower courtyard is a quartz
granodiorite (Figure 49) containing quartz and dominated by
plagioclase feldspar (often rectangular, creamy light gray) with mafic
phenocrysts (large, dark crystals in a fine-grained ground mass) of
the mineral amphibole (small black crystals). Large xenoliths are
present in this rock, too. Note the well-formed plagioclase crystal
laths which show evidence of compositional zoning (growth rings)
which indicate the slow cooling rates of the magma which formed
this rock.
O2
Figure 46. Stop O: Hearst Tower exterior
O4
O3: Seating wall upper and unpolished paver intersections
This granodiorite (Figure 50) is weakly metamorphosed as evidenced
by the subtle alignment of elongated crystals.
O3
O1
O3
Figure 47. Stop O: Hearst Tower Courtyard
Who can find the largest plagioclase xenocryst? We found one that
is 10cm long!
Can you differentiate the xenocrysts from the xenoliths of other
igneous rocks that were likely included as ‘hitch hikers’ as the
magma from this rock intruded into the country rock?
Both the xenocrysts and xenoliths show reaction rims, halos around
the crystals and rock fragments that represent partial assimilation
with the magma after they were picked up.
Figure 48. Stop O1: Anorthosite
Figure 50. Stop O3: Granite
Figure 51. Stop O4: Travertine
Figure 49. Stop O2: Meta-diorite
page 16
O4: Montaldo’s Department Store (220 North Tryon) exterior
cladding
The former five story Montaldo’s Department Store on the northwest
corner of the Hearst Tower plaza was designed 1920 by Louis Asbury
Sr. in Italian Renaissance Revival style. The building housed the
Mint Museum of Craft + Design from 1999-2010. It is clad in white
travertine (Figure 51) similar to that seen at stops E and K.
Stop P: St. Peters Episcopal Church
115 West Seventh Street, Charlotte, NC 28202
St. Peter’s (Figure 52) was the first Episcopal Church in Charlotte
and the parish can trace its origins to 1834. The current building at
the corner of Seventh and Tryon Streets was completed in 1895.
P1: Accent stone
While much of the Church’s construction is brick, sandstone blocks
(Figure 53) were used in the foundation, doorways, stairways and
windows. These sandstones are medium-grained, planar stratified,
brownish red sublitharenites (mostly quartz with rock fragments).
The dark red/black color visible on many of the sandstone blocks
is the result of weathered iron bearing minerals and of pollution.
Restoration efforts have included plastering portions of the faces of
many of the stones with stucco.
Figure 52. Stop P: St. Peters Episcopal
Church
Find a stone where the stucco has chipped away in order to observe
the actual color and grain characteristics of this rock.
These sandstones are likely derived from fluvial deposits found in
Triassic basins (~ 220 million years old) in eastern North Carolina,
including the Deep River Basin which underlies the Durham/Chapel
Hill area. Similar sandstones were used in 19th and 20th century
brownstone construction in major cities up and down the East Coast.
Figure 53. Stop P1: Sandstone
P2: Roof tiles
A common roofing material for this period of architecture, these slate
roofing tiles (Figure 54) are possibly derived from the Ordovician
Martinsburg Formation in Pennsylvania. Can you spot the banding
in some of the tiles? This is the product of the deposition of sediment
layers prior to the metamorphism that changed the stone from shale
to slate.
Figure 54. Stop P2: Slate
page 17
Stop Q: Levine Museum of the New South
200 East Seventh Street, Charlotte, NC 28202
The recently renovated museum re-opened on October 13, 2001.
The museum provides a comprehensive examination of post-Civil
War Southern society, history and sociological evolution for the
city and region, through interactive exhibits, events, lectures and
workshops.
Figure 55. Stop Q: Levine Museum
Q1: Orange-colored exterior cladding
The cladding stone used at street level of the Levine Museum is
from a limestone quarry in Lueders, Texas. The Lueders Limestone
ranges from brown to gray in color and is categorized as a fine to
coarse grained, bioclastic packstone (grain to grain contact with
mud cement) to wackestone (grains ‘floating’ in mud matrix). The
Lueders Limestone contains both fragmented body fossils (ex: shells
in Figure 56) and abundant trace fossils (Figure 57). These trace
fossils record the behavior (e.g. burrowing) of organisms rather
than their morphology. Trace fossils visible in this rock include
planolites, a straight to gently curved horizontal burrow, as well as
arthrophycus.
Figure 56. Stop Q1. Shelly body fossils in
Lueders Limestone
The Lueders Formation is the uppermost member of the Albany
Group which occurs on the eastern shelf of the Midland Basin. This
limestone was deposited during the Early Permian (~275.6 ± 0.7
to 270.6 ± 0.7 million years ago) when a shallow sea covered this
part of West Texas.
Q2: White-colored exterior cladding
This oolitic limestone (Figure 58) was also quarried near Lueders,
Texas. This limestone is a fine grained, grayish white carbonate
grainstone composed of ooids (see Stop A for more information
on ooids) and shell fragments, including gastropods (obvious from
their elongated spiral morphology). Put your nose or a hand lens on
the rock to see the small ooids. The visible swirling pattern in some
tiles is cross bedding. This bedding is due to the deposition of the
carbonate particles in ripples and dunes migrating on the shallow
sea floor.
Figure 57. Stop Q1. Trace fossils in Lueders
Limestone
Figure 58. Stop Q2: Oolitic limestone
page 18
Stop R: Arena Plaza
333 East Trade Street, Charlotte, NC 28202
On the plaza between the Bobcats Arena and the light rail line,
there are several bench sculptures designed by Charlotte artist Paul
Sires. These functional works of art feature a variety of stones from
the Carolinas, Virginia, and Canada. Have a seat on rock that predates the dinosaurs!
R1c
R1b
R1a
R1: Tulip bench sculpture
R1.a: Pink Kershaw Granite
Figure 59. Stop R1: Tulip bench sculpture
The “Pink Kershaw Granite” (Figure 60), quarried in Kershaw, SC, is
a classic granite, but it is technically classified as a porphyritic quartz
monzonite. It is part of the Liberty Hill Pluton and is Carboniferous
to Permian in age (350 to 250 million years old). Large pink crystals
of perthitic orthoclase (pink colored grains) dominate this stone but
albite plagioclase (white colored grains), quartz (clear to translucent
minerals), hornblende and biotite (dark minerals) are also visible.
Some rapakivi texture (see stop E1 for information on this texture)
is visible encasing some of the orthoclase grains.
R1.b: Carolina Pink granite
Figure 60. Stop R1.a: Pink Kershaw Granite
The “Carolina Pink Granite” (Figure 61) is Devonian in age (415 to
355 million years) and is derived from the Salisbury Plutonic Suite
in Salisbury, North Carolina. Its minerals include approximately
45% perthitic (characterized by linear blebs) orthoclase (pink),
25% plagioclase, 20% quartz(clear), and 10% biotite (black).
R1.c: Texas Pearl grey granite
The “Texas Pearl” grey granite (Figure 62) is a Proterozoic (2.5
billion to 550 million years old) granite from the Town Mountain
Granite Suite near Marble Falls, Texas. See stop T for more examples
of granites from the Town Mountain Granite Suite and the Llano
Uplift. Perthitic feldspars (pink) are present, but this rock contains
more quartz than the other two rocks in the sculpture. Sodic rich
plagioclase (white), amphibole and biotite (black) and quartz (gray)
are also present.
Figure 61. Stop R1.b: Carolina Pink granite
Figure 62. Stop R1.c: Texas Pearl grey
granite
page 19
R2: Half Gear bench sculpture
This bench, in the shape of half a gear (Figures 63-65), is known
in the building stone trade as “Virginia Mist Granite”. This unusual
rock appears to be an intermediate igneous rock that has been
metamorphosed as shown by the flow structure (banding of light
and dark minerals). It also includes unusual looking swirls of light
colored plagioclase feldspar and quartz rich veins. Note the latestage cross-cutting diabase veins (dark in color).
Overall the rock may be a Jurassic diabase quarried near Culpepper,
Virginia. The diabase is a fine- to coarsely-crystalline, sub-aphanitic
to porphyritic, dark-gray mosaic of plagioclase laths (long narrow
crystal habit) and clinopyroxene, with some olivine and bronzite
(orthopyroxene) masses. The diabase occurs as dikes and sills
associated with the Culpepper Mesozoic basin.
Figure 63. Stop R2: Virginia Mist granite
R3: Double Leaf bench sculpture
R3a: Crystal Gold White granite
The lighter rock in this sculpture is the “Crystal Gold White Granite”
(Figure 67) and is from Vermillion Bay, in northwestern Ontario.
The Nelson Granite company actively quarries syn-tectonic to pretectonic granites and granodiorites of the Archean Vermilion Granitic
Complex. Minerals include sodium rich plagioclase feldspar (white),
potassium feldspar (cream) and biotite and amphibole (black).
Figure 64. Stop R2: Virginia Mist granite
R3b: Forest Green granite
“Forest Green Granite” (Figure 68) is actually a gabbro from a
quarry operation in Saint Sebastien de Frontenac, Quebec, Canada.
The gabbro is Cambrian to Devonian in age and includes calcicrich plagioclase (dark), pyroxene (black in the unpolished surface)
and amphibole. The mineral composition and shape of the grains
in this rock provide evidence that it is ‘cumulate’, meaning that
most of the liquid was squeezed away during its crystallization in a
magma chamber, leaving behind this assemblage of the early (high
temperature) crystallizers on Bowen’s reaction series.
R3a
Figure 65. Stop R2: Virginia Mist granite
close up
R3b
Figure 66. Stop R3. Double leaf bench
sculpture
Figure 67. Stop R3a. Crystal Gold White
Granite
Figure 68. Stop R3b. Forest Green Granite
page 20
Stop S: Ritz Carlton Hotel
201 East Trade Street, Charlotte, NC 28202
This 17 story (200 feet) post modern building completed in 2009 was
designed by Smallwood, Reynolds, Stewart, Stewart and Associates
and is LEED Gold certified.
S1: Exterior upper cladding and lobby flooring
The pink and grey “marble” used in the main entrance walls and
flooring in the lobby of the Ritz Carlton hotel is a fossiliferous
limestone quarried in Friendsville, Tennessee, about 35 km
southwest of Knoxville. How many different fossils can you find?
We note at least three in this packstone to grainstone limestone:
hemispherical bryozoan fragments as well as brachiopod (visible
as small black arcs in Figure 70) and crinoid fragments. This pink,
coarsely crystalline limestone is from the Holston Formation, a ~70200 meter thick stratigraphic unit within the Chickamauga Group of
the Valley and Ridge geologic province of eastern Tennessee.
The limestones of the Holston Formation formed during the Middle
Ordovician (~460 million years ago) in shallow water on the southern
continental shelf of Laurentia. In this environment, bryozoandominated reefs flourished but the high energy of the waves often
broke pieces of limestone from the reef. Such fragments of bryozoans
rolled across the seafloor, together with fragments of other animals,
and gradually built up porous shoals of coarse-grained limestone
fragments. These fossils are as coarse as ~1-2 cm in diameter and
can be seen in the cut and polished surfaces of the limestone.
In the Late Ordovician, a volcanic island arc collided with the southern
margin of Laurentia causing the Taconic orogeny. Sedimentary rock
strata on the continental margin, including the Holston Formation,
were pushed landward, folded, broken, stacked and buried as the
Taconic Mountains rose. The pressure associated with the collision
and burial compacted the limestone, and cemented the grains
more firmly together. (description from http://academic.brooklyn.
cuny.edu/geology/powell/613webpage/NYCbuilding/TennesseeMarble/
TennesseeMarble.htm)
S1
S2
Figure 69. Stop S. Ritz Carlton Hotel
entrance
Figure 70. Stop S1: Fossiliferous limestone
Figure 71. Stop S1: Fossiliferous limestone
The natural bedding in the cut limestone blocks has been used to
form geometric patterns in the floor (Figure 71). This limestone can
also be found in the J.P. Morgan building and Grand Central Station
in New York City.
S2: Ground level exterior cladding of the Ritz Carlton hotel
and unpolished pavers in the main entryway
This migmatitic (meaning the gneiss is undergoing the initial stages
of melting) gneiss (provenance unknown) likely had a granitic parent
body which was subjected to intense heat and pressure causing
partial melting and the development of the beautiful gneissic
banding that is visible. The rock appears to have been subjected to
multiple subsequent metamorphic events resulting in folding of the
gneissic banding.
Figure 72. Stop S2: Migmatitic granite
page 21
S3: A large infilled geode in the Ritz-Carlton lobby
This large geode (Figure 73, provenance unknown) has been cut in
half and polished. The stages of filling of the geode by chalcedony
can be seen as layers in the polished surface. Geodes can form
in any cavity (vug) within which dissolved silicates or carbonates
precipitate out and form the multiple layers visible in the interior of
the geode.
Can you spot the “Virginia Mist Granite” from stop R in the lobby?
Can you find the stylolites (already described in Stops D and N) in
the lobby floor? Continue to the elevator to find a stunning example
of an ammonite fossil.
Stop T: Hilton Charlotte Center City / One Wells
Fargo Building
222 East 3rd Street
T1: Texas Pearl granite
Figure 73. Stop S3: Geode sculpture
One of the paving stones as well as the building and fountain facing
stone comprises a light pink granite known as “Texas Pearl” from
Llano, Texas (Figure 74 & 75). This Proterozoic granite is from
the Town Mountain Granite suite and is comprised of albite (white
plagioclase feldspar), orthoclase (pink feldspar), quartz biotite and
amphibole (dark minerals). Here is yet another example of a rock
with some Rapakivi texture.
T2: Texas Pink granite
Another one of the paving stones is a dark pink porphyritic granite
known as “Texas Pink” from Granite Shoals, Texas (Figure 76). This
Proterozoic granite is also from the Town Mountain Granite suite
and is comprised of potassium feldspar (pink colored grains), sodic
plagioclase (white colored grains), quartz and biotite.
The Town Mountain Granite suite (TMG) of the Proterozoic Llano
Uplift of central Texas is generally a pink, very coarse grained,
porphyritic granite with accompanying pink coarse-grained nonporphyritic granite. Mineralogically, the TMG consists primarily of
plagioclase feldspar, potassium feldspar (microcline), and quartz with
biotite and/or hornblende. Accessory minerals commonly include
titanite (sphene), zircon, magnetite and/or ilmenite, and apatite
with fluorite, allanite, and/or pyrite being present in some rocks.
Texturally the granites are dominated by the large pink microcline
feldspar crystals. Differences in the color, shape, or amount of these
microcline feldspar crystals are responsible for much of the differing
appearance of building stone varieties. Faint to well-developed
alignment of these large crystals (magmatic foliation) occurs
somewhere in most intrusions. Regionally, the granites intrude
multiply-deformed schists, gneisses, and other metamorphic rocks
of the Llano Uplift. (from http://uts.cc.utexas.edu/~rmr/tmg.html)
T1
T2
T4
T3
Figure 74. Stop T: Hilton Charlotte Center
City and One Wells Fargo Center
Figure 75. Stop T1: Texas Pearl granite
Figure 76. Stop T2: Texas Pink granite
page 22
Commercial quarry operations have been underway since 1882
when TMG was first quarried to construct the Texas Capitol building.
T3: Rockville White granodiorite
A third paving stone is a light-colored phaneritic granodiorite
(Figure 77) known as “Rockville White” from Rockville, Minnesota.
This Proterozoic granodiorite is a late intrusion associated with the
Penokean Orogeny (see below) and is comprised of oligoclase (large
white plagioclase feldspar), possible quartz, amphibole and biotite.
The Penokean orogeny was a major event in the formation of the
North American craton. The orogeny lasted about 10 million years
and occurred in two phases. During the first phase, the PembineWausau island arc terrane collided with the ancient North American
craton, along with volcanoes formed in its back-arc basin. The
second phase involved a micro-continent called the Marshfield
terrane, which today forms parts of Wisconsin and Illinois.
Figure 77. Stop
granodiorite
T3:
Rockville
White
T4: Dakota Mahogany granite
A fourth variety of paving stone at this site is a dark gray to black
granite (Figure 78) known as “Dakota Mahogany” from Milbank,
South Dakota. This Archean granite is part of the Milbank Granite
Suite. It contains orthoclase feldspar, sodic plagioclase, quartz and
biotite.
Figure 78. Stop T4: Dakota Mahogany
granite
The authors would like to thank the additional students of John
Bender’s Economic Geology class for their research on the project.
We especially thank Dr. Scott Hippensteel for his thorough and
helpful review of the tour.
page 23
Uptown Charlotte Building Stones World Provenance