Archive for the ‘Oakland stone’ Category

Oakland building stones: Sandstone

19 September 2016

For many years, timber was the default material for Bay Area buildings. Only substantial institutions like governments, banks and a few wealthy churches were sheathed in masonry — solid stone — and time and again, earthquakes were their undoing. Sandstone was chosen for the walls of two major Oakland churches, First Baptist and First Unitarian.


First Baptist, on Telegraph Avenue at 22nd Street, was one of Julia Morgan’s earliest commissions, although she didn’t have a say in its looks. The Romanesque Revival building, inspired by the Aachen Kaiserdom, was designed by another architect whose delays in getting it built led the congregation to fire him once the exterior walls were up, in 1904. The day the church was to vote on Morgan’s design for the interior was 18 April 1906, and early that morning the San Francisco earthquake badly damaged the exterior. She took on the job of rebuilding it, then finishing to her own specifications a magnificent sanctuary inside.

The stone, to all appearances, is from the Greystone Quarry south of San Jose. It’s the same golden sandstone of Eocene age (~35 million years) used for the core buildings of Stanford University and other landmark structures like the Carson City Mint in Nevada, Lick Observatory and the old San Jose Post Office, now part of the San Jose Art Museum. I wrote about this stone for KQED a few years back. The stone blocks have a rugged “quarry face” on the exterior but are nicely dressed on the sides. The flat sides qualify them as ashlars, as opposed to fieldstone like you’d use in free-standing stone walls.


The building also suffered damage during the 1989 earthquake. In this view you can see the seismic bracing, covered in gray, on the north wall that was installed at the time.


The First Unitarian Church, at 685 14th Street, was designed by Walter Mathews in the elegant Richardsonian Romanesque style. Construction began in 1890.


Stone was an important design choice, inspired by “a spirit of civic pride.” All of the building’s materials were sourced in California. The sandstone is a thick veneer, in quarry-faced ashlars like first Baptist. However, the stone is a cool gray, very fine grained, and is apparently not from Greystone Quarry. Parts of the building are faced in neat rows (courses) and arches.


This stairwell bay is pleasingly laid in random-coursed ashlars, a system that avoids a regimented look and is probably stronger too.


At its opening on 6 September 1891, a hymn written for the occasion began with the verse,

“The forests gave their oak and pine,
The hills their stone and clay,
And fashioned by the builder’s art
Our temple stands today.”

The building suffered light damage in 1906 and 1989, but repairs in both cases took several years.

The church’s Historic American Buildings Survey (HABS) report is full of deep technical and historical detail.

In both buildings, the sandstone shows signs of deterioration after more than a century of exposure.

Oakland building stones: Verd antique

5 September 2016

California’s state rock is serpentine, and in this blog I’ve picked up, photographed and defended it against detractors. I’ve called serpentine beautiful, adorable, inspiring and more, but I’ve never called it a building stone. However, it can be.

Serpentine in its Sunday best is called verd antique. This closeup is from the iconic I. Magnin building at Broadway and 20th Street.


It resembles a particularly psychedelic marble — a translucent deep jade-green shot with intricate white veins. Petrologically, though, it is nothing like marble and a lot like soapstone. It consists of magnesium-based silicate minerals that are harder and more chemically robust than the calcite or dolomite that makes up marble.

Verd antique is all over downtown Oakland, usually as a subsidiary element at the sidewalk level. The building on 17th Street between Telegraph and Broadway has a particularly large expanse of it.


The Fox Theater building is another notable example. But in this post I want to draw attention to four buildings that do more with verd antique. The I. Magnin building (built 1930) naturally comes first, its entire first story richly faced with this stone.


The Foulkes Building at 419 15th Street (built 1924) has a high facade of verd antique with bronze decorations.


The Moyles-Kappenman building (built 1928), longtime home of Lobe & Velasco Jewelers, has a lovely front of verd antique on 1617 Broadway and an identical one at its other end on 1618 Telegraph.


Finally we have the otherwise undistinguished Wells Fargo building at 2040 Franklin Street, where the public-facing elements (entrances and ATM) are framed in verd antique.


The reason that all of these stones look the same is that for nearly a century a single quarry in Rochester, eastern Vermont, has been supplying the trade with Vermont Verde Antique(tm) stone. It is geologically special because it was squeezed two separate times, like twice-cooked fries, between colliding tectonic plates during the Paleozoic Era. As the supplier’s website puts it, it owes its origin to “highly sheared ultramafic rocks that have been rewelded and metasomatized by the process of serpentinization.” The lighter-colored “Cardiff Marble” serpentine from northern Maryland was once popular but is no longer produced. That stone is found in the White House’s Green Room, the National Archives rotunda and other places in Washington DC.

Verd antique gets its name from the Italian verde antico, “ancient green.” It was popular in Byzantine architecture. Oakland has a few pieces of European-style, brecciated verd antique to be seen here and there.

The stone industry considers verd antique a type of marble (it’s metamorphic and takes a polish) and follows ASTM standards for its manufacture, but verd antique is really its own beast.


You can’t do much with California serpentine except admire it. For an example, see the ecstatic response of an out-of-state geologist to San Francisco’s Marshall Beach exposures.

Oakland building stones: Granite variations

29 August 2016


Oakland’s buildings embody history and geology in the different types of stone that compose their facades. So how about granite?

California began producing granite soon after statehood, in a stonecutting district near Sacramento where rail and barge transport was handy.

At the time Oakland’s third City Hall was being designed, around 1910, many large quarries in the Sierra were supplying the market, and the architects chose “Sierra White” stone from a quarry near Madera, probably the McGilvray Quarry. The same district still produces Sierra White granite for the great Coldspring empire.


This fine-grained granite is excellent for carving and for resisting the attacks of urban pollution. Its neutral color works well with the building’s superb ceramic tiles and marble. Many of San Francisco’s notable buildings (the St. Francis Hotel, Bank of California and Old Custom House among them) also use Sierra White.

Buildings of later vintage take advantage of stone from more distant sources. The Lake Merritt Tower building at 155 Grand Avenue, built in 1990, features a splendid granite with extremely coarse grains, not typical of California. The granite benches around the building use the same stone in a polished finish that displays it especially well.


The building itself employs the same granite with a flamed or thermal finish. It’s produced by running stone slabs through a set of gas-fired torches. The sudden thermal expansion shatters the minerals and, properly controlled, yields this rugged surface.


The Caltrans building next door, formally named the Nicholas C. Petris State Building and finished in 1992, is faced with a pink granite from Texas in both polished and sandblasted finishes. Here’s a closeup.


What are we looking at here? Time for the geology part. First of all, to stone dealers “granite” means only one thing — a coarse-grained rock (1) hard enough to take a good polish and (2) not marble, serpentine or quartzite — but that thing is a very broad one. Stonecutters came centuries before geologists, and what they say goes.

Geologists don’t call every granite building granite. “Black granite,” for instance, is gabbro. Scrupulous geologists would call all the stones in this post “granitoid,” meaning one of a broad set of coarse-grained rocks made of feldspar and quartz in various proportions. Real petrological granite has a narrower set of proportions. None of these stones has the 20 percent quartz that would qualify it as true granite. I know you’re disappointed. But the feldspar makes a great building stone.

In the picture above, quartz is the clear stuff that looks gray. Feldspar comes in two main types. The white grains are plagioclase feldspar, and the pink ones are alkali feldspar. (A pink color is unusual; it ranges from white to buff to red.) The black grains are typically hornblende, biotite (black mica) or both.

The gorgeous Texas Pink granite of the Lake Merritt Plaza complex, at 20th and Harrison streets, shows these minerals more vividly.


I do think this is Oakland’s most beautiful building stone. Texas Pink is a brand (not the kind you burn on steers), also from the Coldspring empire. It’s quarried from Granite Mountain, about an hour out of Austin and near the amazing dome of pink granite preserved in Enchanted Rock State Natural Area.

Texas Pink granite was also used, a bit more adventurously, in the AC Transit headquarters building at 1600 Franklin Street.


I don’t know in what year the building was constructed, but I have the impression that Oakland architects are finished with Texas Pink granite for the moment. Metal and glass is the default exterior of today’s large urban buildings. In their lavish lobbies and interiors, though, stone is still the right stuff.