Stony Creek Granite

Stony Creek Granite is the pink stone under the Statue of Liberty. It comes out of Branford on the Connecticut shore, it has been quarried since 1858, and the swirling figure that makes it recognizable on sight is not a granite texture at all. It is foliation, and the United States Geological Survey names the rock a granite gneiss.

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The swirl is the geology

The USGS maps the unit as the Stony Creek Granite Gneiss and dates it to the Neoproterozoic, part of the Avalon terrane: crust that formed somewhere else entirely and was welded onto North America later. The mapped description is "red to pink, unevenly medium to very coarse grained, variably foliated granite or granite gneiss", made of oligoclase, potassium feldspar and quartz, with minor biotite and magnetite, sporadic garnet in the foliated varieties, and local muscovite.

Two things follow from that for anyone specifying it.

The pink is potassium feldspar, and the darker sweeps are biotite and magnetite. That is why the color reads warm salmon rather than the gray of most northeastern granites.

The banding is a metamorphic fabric. A true granite cools with its crystals pointing in no particular direction, which is why granite looks evenly speckled. Stony Creek's crystals have been combed into alignment by directed pressure, and the bands you see on a polished face are that alignment. The trade has always sold it as granite because that is how it cuts, wears and weathers. The name describes the behavior, not the rock, which is the same bargain that gave Tennessee Pink Marble its name at the other end of the country.

A fabric with a direction also means the stone has a grain, and that has a practical consequence covered in the next section.

Where it comes from

The quarries sit at Stony Creek in Branford, New Haven County, on the stretch of Connecticut shore facing the Thimble Islands. Benjamin Green opened Branford's first quarry in 1858, six years after the railway reached the town in 1852, and the two facts are connected: rail is what made shipping building stone out of a coastal village worth doing.

The trade grew quickly from there. The Red Granite Company was founded in 1876 and later became the Stony Creek Red Granite Company. Norcross Brothers bought property at Stony Creek in 1887 and became the most successful operation in the area. Inside fifty years the quarries around Branford employed roughly 1,800 men, drawn from Italy, Ireland, Sweden, Finland and Spain, and the town had to build the housing, shops and schools to hold them. Finished stone left by schooner and by rail, reaching as far as Chicago and New Orleans.

One operation works the stone today, on the same ground.

What the tests actually say

Stony Creek Quarry publishes its full ASTM test reports, run by the Natural Stone Institute laboratory in January 2020. That is worth more than any adjective, so here are the numbers against ASTM C615, the specification for granite dimension stone.

It clears every requirement, and absorption at less than half the permitted maximum is the number that matters most for a stone used on sea walls and in a freeze-thaw climate. Water that cannot get in cannot freeze and split the face.

The grain shows up in the results. Because the rock is foliated, the laboratory ran the strength tests in two orientations relative to the rift, and they do not match: compressive strength measured 20,470 psi in one orientation and 22,860 psi with the rift parallel, about twelve percent apart. Modulus of rupture runs the other way, 1,760 psi perpendicular against 1,640 psi parallel. Neither figure is bad, and both pass comfortably. The point is that this stone has a direction, so on load-bearing or long-span pieces it is worth agreeing the orientation with the quarry rather than leaving it to the saw.

One caution the laboratory itself prints on the abrasion report: hard, coarse-grained stones both polish and abrade under the test wheel, so abrasion figures for granites carry a wider spread than the single average suggests.

Where you have already seen it

The nineteenth and twentieth century work is the reason the stone has a reputation: the pedestal of the Statue of Liberty, the foundations of the Brooklyn Bridge, Grand Central, Grant's Tomb, the Battle Monument at West Point, South Terminal Station in Boston, the Freer Gallery and the National Air and Space Museum in Washington, the Bulkeley Bridge in Hartford, and the AT&T headquarters in New York, now the Sony building, completed in 1984. It traveled further than that: Chifley Towers in Sydney and the Stadtsparkasse at Mülheim an der Ruhr in Germany.

The recent list is the more useful one, because it shows the quarry is still supplying at that standard. Since 2008 it has cut stone for the Statue of Liberty Museum, the Cooper Hewitt National Museum of Design, MIT, One Dalton Four Seasons in Boston, the Newark Museum, and repeatedly for Columbia University and Yale, including the Peabody Museum's Cretaceous Garden and the granite pedestal under its Torosaurus. In progress: 550 Madison, the Smithsonian Hirshhorn Museum and Sculpture Garden, and the Metropolitan Museum of Art AAOA Galleries.

The pedestal went up in the 1880s and the museum on the same island opened in 2019, both faced in stone from the same Branford ground. Very few building stones anywhere can show a gap like that with the quarry still open at the end of it.

Applications

Marine and sea wall work: the application that separates this stone from most decorative granites. Sea wall block, jetties and coastal armor need mass, very low absorption and resistance to salt and freeze-thaw, and Stony Creek is quarried in block sizes that suit it.

Exterior cladding and ashlar: the historic core of its use. Split wall veneer and sawn panels, with the foliation giving a facade movement that a uniform granite cannot.

Paving, steps and curbing: hard-wearing at Mohs 6 to 7, and the reason it appears across so much New York City park and plaza work, from Battery Park to Flushing Meadows.

Monuments and memorials: it holds a crisp arris and carved lettering, which is what put it on the Battle Monument and keeps it on memorial work today.

Landscape and retaining walls: posts, blocks and irregular pieces, mostly a regional New England and Mid-Atlantic market.

Heritage restoration: anything being patched or extended on the list above needs stone from this quarry, because no other source matches the color and figure.

Buying it

Stony Creek Quarry Corporation at Branford is the working source, and it describes itself as the authentic source of Stony Creek Granite. Its range covers blocks, granite slabs, split wall veneer, posts, sea wall block, steps, pavers and aggregate, and it publishes the ASTM reports quoted above rather than keeping them behind a sales conversation.

As with any single-quarry stone, availability and lead time come down to one operation rather than a competitive market, so engage early on anything large or color-matched. If you are matching existing work, bring a sample: the foliation means two blocks from the same quarry can read quite differently once polished.