Archive for the ‘Oakland stone’ Category

Oakland building stones: Kaiser Center’s dolomite

18 July 2016

During yesterday’s OHA walk around some of Oakland’s building stones, I was pleased to bring out an underappreciated aspect of this great city landmark.

Kaiserctr

The Kaiser Center, like City Hall, is one of Oakland’s signature buildings. When construction finished in 1960 the curving, T-shaped office tower was so iconic that Ansel Adams is said to have photographed it, presumably giving it the same sheen of grandeur he gave Half Dome. (I couldn’t find that image, although Rondal Partridge also photographed it, which is just as good.)

The photo above shows the butt-end of the 7-acre Kaiser Center complex, at Webster and 21st streets. In the foreground is the parking structure/commercial space that holds up the wonderful rooftop garden.

The Kaiser Center is famous for its extravagant use of glass and metal, specifically aluminum, Kaiser Aluminum’s principal product and a design element dictated by Henry J. Kaiser himself. But I spoke to the group about the third element that embraces the metal and glass in a gracious unity — the white stone cladding.

As you walk around the Center, the cladding appears pleasantly rough yet perfectly homogeneous. It’s not a veneer of solid stone, nor is it some kind of textured concrete. Neither is it painted. It’s an extraordinary material. After 55 years of weather, it still looks white and crisp and fresh.

Nearly all of the cladding is out of reach. Some panels touch the ground along the curving roadway behind the main tower, but that’s too hazardous even for your typical roadside-loving geologist. However, at the left edge of the photo is a little section of wall where the architects felt obliged to extend the cladding to the sidewalk. That’s the only safe place to examine it.

Kaiserctrstone

The backing is concrete, but the aggregate that makes up the face is a pure white stone. Steel scratches it, therefore it is not quartzite, which was my first guess. It has the frosty luster of a carbonate, but it doesn’t fizz under dilute hydrochloric acid (I always carry some). Therefore it is not ordinary limestone or marble. It’s something much less common: coarse-grained dolomite, a stone with its own place in Kaiser’s history.

Whereas limestone and marble consist of calcite (CaCO3), dolomite rock or dolostone consists of the mineral dolomite (CaMg(CO3)2), in which magnesium takes the place of half of the calcium. It has many industrial uses, and the Kaiser conglomerate has mined it in several different quarries.

During World War II, magnesium metal was in great demand, especially for aircraft. The supply of magnesium ore, magnesite (MgCO3), was very tight. (Magnesite was mined at this time south of Livermore, in Del Puerto Canyon.) Kaiser sought a way to produce magnesium metal from dolomite using the Hansgirg process, but the process was plagued with difficulties. The magnesium program was known as one of Kaiser’s biggest headaches.

Henry Kaiser was closely involved in the design of the Center — indeed, it’s said he intended to live there. One of his conceits was that the materials, as much as possible, should be supplied by Kaiser companies. His architect, the Los Angeles modernist Welton Becket, was noted for his use of natural stone cladding.

Kaiserctrstoneclose

I imagine that Becket and Kaiser were pleased, each for his own reasons, to showcase the exceptionally pure dolomite from Permanente Metals’ large Natividad quarry, a few miles north of Salinas. I feel quite sure that’s what this is.

More reading:

“Looking Down on Creation” in The Monthly, Nov 2006

“Five Painterly Vistas from Kaiser Rooftop Garden” in The Urbanist, Mar 2011

The Natividad quarry (bottom of the page), at Quarries and Beyond

Working rocks

14 September 2015

Last week I made another visit to Knowland Park in preparation for my two upcoming Wild Oakland walks on September 20 (tickets still available) and October 4 (no tickets needed). I’m holding off on posting about the park’s geology until after these events, but it’s hard to wait.

Meanwhile, here’s something different. Oakland has plenty of excellent native rocks, but the days are long past when Oaklanders could shop for Oakland stone at an Oakland quarry. Today newer places must make do with more anonymous stones from distant sources. They do their jobs with stolid competence and the occasional dash of flair.

This roadside lot on Cameron Drive uses guard rocks to discourage parking and keep runaway vehicles from breaking the wall. They’re picturesque, but kind of brusque.

roadsidestones-cameron

Sobrante Park Elementary School has this splendid green boulder by its front entrance. It’s not serpentinite but, most likely, a beautifully chloritized basalt from the Franciscan Complex. The two neighboring boulders are sandstone. I think their job is keep runaway vehicles from the building, although neither Topanga Drive nor El Paseo Drive is a high-speed thoroughfare.

schoolstone

And down by Lake Merritt, the latest Measure DD improvement, the Sailboat House Shoreline Project, has made the shoreline more wildlife-friendly. The marsh vegetation will have to wait for the rainy season, but the infrastructure is in place.

lakesidestones

These boulders are undistinguished sandstone, but they’re laid with care. I predict that the gulls will be cracking mussels on them, if they aren’t already. The rocks will also allow people to step into the marsh without kicking up the reeds and mud. And they’ll keep runaway vehicles out of the lake. Hmm, there seems to be a common thread here.

Some East Oakland stones

31 January 2015

Oakland’s rocks aren’t all in the ground. They’re in our yards and homes, too. Here are a few presented in the order I found them lately.

There’s a house on 60th Avenue that stopped me in my tracks, its walls studded with stones. A neighbor down the block told me “Oh yes, those are wonderful! We looked at that house when we were buying in this neighborhood. The owner’s daughter runs a preschool across the way.” Click that one for an 1100-pixel version.

morse-at-60th-450

A few weeks later I visited Best Avenue, high in Maxwell Park, and was arrested by the front yard here. Sometimes rocks, like people, look best with painted faces.

bestrox2

A block away is another property treated by the same decorator.

bestrox1

And just yesterday this basket of painted stones seized me by the eyes. It’s at the Free Oakland UP gallery and workshop, in the Loard’s plaza at Coolidge and MacArthur.

oakland-up-rox


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