Let's meet marble and the metamorphics

This post ran on 14 October 2008 originally.
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That sounds like the name of a Do-Wop band. So since I touched on igneous rocks in general and granite in particular yesterday, today I want to talk about the metamorphics.

My diagram above shows sedimentary rocks on a sea floor being subducted under a tectonic plate. That sedimentary rock will turn into metamorphic rock given enough time, enough heat and enough pressure. So what was once sediment on the bottom of the sea turns into metamorphic rock as it gets pushed down into the slow cooker that sits directly below our feet. If it doesn't run into anything, it will turn into an igneous rock eventually. But then I wouldn't have anything to write about.

So in our case, the now metamorphic rock is going to run into another continental plate and instead of continuing its long journey down, it's going to be thrust upward like in this diagram.

The blue section in this diagram shows how metamorphic rocks end up back on the surface of the earth after their time spent below ground. That blue section is how we get three common metamorphic rocks used in homes: marble, quartzite, soapstone and a fourth, mysterious stone called serpentinite. I'm going to write a post on soapstone later, so for now I'm going to concentrate on marble, quartzite and serpentinite.

Everybody knows what marble is but what a lot of people don't know is that it used to be limestone, a sedimentary rock. So even though the chemistry of the original limestone and the resulting marble are identical, their molecular structures are different thanks to time spent in the depths of the earth. The same thing happens to turn sandstone into quartzite. Serpentinite is another metamorphic rock that's usually mislabeled as marble (Rainforest Green and Rainforest Brown are examples of serpentinite). Serpentinite starts out as ultramafic rock in the mantle of the earth that gets thrust upward. Serpentinite never spent any time at the surface of the earth and it isn't a transformed sedimentary rock. It's instead the transformed, formerly molten core of the earth.

OK, real life example time.

Here's a slab of Carrera marble. It's a pretty common stone so far as marbles go and most of it starts at around $60 a square foot when it's being made into a kitchen counter. It's composed of calcium carbonate and other minerals and that's what makes it softer and less stain resistant than granite. Despite what everyone claims are its negatives, I'd be safe in saying that it's my favorite counter top material. It's a classic, it holds a temperature perfectly, it looks great and 11 million Italian families can't be wrong. Embrace the stains people.

So here it is in a traditional kitchen. The subway tile on the back wall is also made from Carrera in this kitchen. In life, this is a gorgeous kitchen in a nearly timeless style.

Carrera also looks great in a modern setting. The William Ohs kitchen shown above proves that pretty well.

Marble can also be black with white veins of silica in it and that's stunning in its own right. Although at the end of the day, I think that white marble's easier to work with aesthetically.

This is a piece of white quartzite my client fell in love with last week. White quartzite often gets mislabeled as marble, but they are very different stones. Marble is composed of calcium carbonate and quartzite is composed of silica. The two stones behave very differently. As silica, quartzite will be harder and less prone to staining than marble will. If you look at quartzite up closely, you can see that it has a grainier appearance than marble does. That's from its once having been sandstone.

Quartzite usually has some bright colors in it on a white background. When it looks like this it's often mislabeled as granite and that's unfortunate because it's not granite. Quartzite is more porous than granite is despite their being made from the same elements essentially.

This is a quartzite from Brazil that's always mislabeled and sold as a granite. It's usually called Blue Louise and it is an eyeful. Again, it's beautiful as a piece of stone but as Tim Gunn would say, it's a lot of look. Proceed with caution.

The other big difference between quartzite, marble, serpentinite and granite is the price. Quartzite and serpentinite are always wickedly expensive whether they're labeled properly or not. Marble and granite tend to be more affordable.

Finally, the slab of stone above is always labeled as a marble and it's usually called Rainforest Brown or Rainforest Green. It's not a marble though, it's a serpentinite that's been pushed up from the very bowels of the earth. It's made from a veritable soup of elements ranging from manganese, cobalt, nickel, iron and silica. Even though it's sold as a marble, it's a lot more resilient than marble is and it's usually harder. These stones are great to use in bathrooms, but I wouldn't want to prepare food on them in a kitchen owing to their toxic mineral content.

Granted, the amounts of cadmium, chromium and the rest of them are trace amounts; but I'd like to keep my cadmium intake down to zero thank you.

So there's my run through of some common metamorphic rocks. Tune in tomorrow when I tackle the sedimentary rocks people welcome into their homes.

Here's a working definition of granite

This post ran originally on 13 October 2008

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The term granite, as it's used commercially, is a bit of a generic term. Now I'm not a geologist but I do have an understanding of the fundamental geology that goes into the dimensional stone that ends up in peoples' homes.

Granite's generally accepted to be an igneous rock composed primarily of silica that's formed in the mantle of the earth as magma gets squeezed between cracks in the earth's crust. As a liquid at that point, the magma tries to rise to the surface. It cools very slowly and under very high pressure then forms what are called batholiths --essentially huge domes that lie below the surface of the earth. These large formations are exposed later through the actions of erosion and thrust faulting. Due to the high pressure under which the magma cooled, the component minerals in it (quartz, feldspar, aluminum oxide, iron oxide, etc.) can crystallize. That crystallization is what makes granite granite.

I bring that up because of this granite right here, commonly called Baltic Brown.

You can see from this close up that Baltic Brown has circular crystals in it. They are in varying sizes but most of them are about two inches in diameter. Those round crystals are made from potassium feldspar and they formed about a gazillion years ago as some magma cooled underneath what is now Finland.

About eight years ago I got into it with a salesperson at a granite wholesaler who claimed that those round shapes were the remains of a stand of young trees that were run over by a lava flow and got fossilized in the process. People who don't understand what they're selling are a pet peeve. Claiming to have fossils in a slab of granite goes beyond not knowing and crosses the line into the idiotic. I don't expect granite salespeople to be able to rattle off the names of the component minerals that make up what they're selling, but some basic knowledge is most definitely in order.

Granite that ends up as counters gets cut into slabs and polished. From the cut stone, you get a really nice cross section of the crystal structure of a particular granite. Those crystals are where granite gets its sparkle and depth. A granite that was left to its own devices as it cooled and formed over the millennia will have a pretty regular pattern and color.

But when granite's actually moving as it cools, or if it runs into water, all sorts of things happen to it. A lot of times granite will run into other kinds of rock as it moves, so it will have incursions of schist and skarn and a host of other materials in it. A lot of times water will make iron oxide gravitate into cracks in the rock. Every component mineral in a granite has its own characteristics and reactions and that non-uniformity is at the root of granite's appeal. The slab below has incursions as well as lines of iron oxide in it.

It's an interesting stone as a stone, but it's a lot to try to pull off in a kitchen counter. I mean, it's pretty loud. Something like that I'd like to hang on a wall to admire. It tells a really compelling story but it's not something I'd want to see in one of my kitchen projects.

Patterns like that granite above are still pretty popular though that popularity has crested and is starting to wane. People are starting to look for other materials to use as counters and that's what I'll be writing about all week. Woo-hoo!

But in the meantime, if you like granite then get granite. Don't believe the stories of its propensity to stain or crack or even be radioactive. Almost every negative you hear about granite is chatter generated by a competitive marketplace. I have never actually seen someone stain or crack a granite counter. Nor have I ever heard of someone who had to reseal their counters. The radon hype is yet another non-story generated by the solid surface people to prop up their decidedly inferior products. Granite is harder than just about anything it will come in contact with and it will continue to look as good as it did the day it went in for the rest of the time you have it.

But let's look at some options anyhow. Tomorrow's going to be marble and the metamorphics.

Revisiting the rocks in my head

This post ran on 13 October 2008 originally
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Rocks are divided into three categories: sedimentary, metamorphic and igneous. A lot of times these three classes are referred to as phases because each class can morph into each of the other classes over long periods of time. But that's can morph, it isn't automatic.

In English, those three classes can be pretty broadly defined like this: sedimentary rocks are formed by compacted sediment, metamorphic rocks are rocks that are transformed by heat and pressure after they're already formed and igneous rocks are formed by cooling magma. Some examples of sedimentary rocks are limestone and travertine. Some metamorphic rocks are marble, quartzite, soapstone and slate. Finally an igneous rock that's in a lot of peoples' homes is granite.

In the chart above, there's a delineation made between intrusive and extrusive igneous rock. Intrusive means that a formation of igneous rock rises into the earth's crust but doesn't break the surface. Not breaking the surface results in a very particular crystal structure. Extrusive igneous rock breaks the surface and cools quickly when not under pressure. This results in a different structure even if the magma has the same composition.

So there's my breakdown of the three classes of rock. There are examples of all three classes that end up being pressed into use by humanity and I'll be spending some time explaining them further. First up will be granite.

A mid-century modern prosthetic leg

This post ran on 22 September 2008 originally.
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I came across this on Apartment Therapy this week and I couldn't pass it up.

I love the work of Charles and Ray Eames as I've said before on many occasions. In 1956, the Eames' released their Eames Lounge and Ottoman through Herman Miller. Herman Miller still produces them now, but in 1956, the Eames/ Herman Miller combination hit pay dirt and released an instant classic. This chair is a design icon for obvious reasons. Designers go ape over it still and it remains as popular now as it was at the time of its unveiling.


An industrial designer named Joanna Hawley took her inspiration from the Eames Lounge and Ottoman and used that inspiration to design a prosthetic leg while she was a design student at Carnegie Mellon University. Hawley partnered up with Kayhan Haj-Ali-Ahmadi, a pre-med student. Kayhan's knowledge of anatomy and Joanna's design skills combined to terrific effect and the fruit of their partnership speaks for itself.
When I think of prosthetic limbs, If I think of prosthetic limbs, the idea that they should be beautiful never occurs to me. When it comes to medical devices, I always assume that function trumps form every time. Who says they can't work together? Clearly, not Joanna Hawley.


In her own words and from her website:

Prosthetics generally lack humanity, style and grace. Often, they look much like landing gear and make the wearer uncomfortable, self aware, and sometimes depressed. By channeling the Eames' use materials and iconic style, we designed a leg with Steve McQueen in mind. We sought to convey a creative use of positive and negative space, a balance of materials and a reflection of the wearer.

I corresponded with Joanna Hawley a bit the other day and I asked her why a prosthesis? Here's what she had to say:

Today's generation is faced with the Iraqi war, particularly the reality of soldiers coming back without limbs. Diabetes is also the leading cause of amputees in America, which is a little known fact. Finally, as an Industrial Designer, its my job (and passion!) to think of ways to improve people's lives. All these reasons simply rolled into one very intense and exciting project. I've always been a huge fan of Ray and Charles Eames (as you can probably tell by the rest of my work) and I wanted to give this prosthetic a very eye-catching aesthetic. I know veneering can be polarizing, but so far people seem really excited by the possibilities. And really, that's what the point of the project was, to identify the possibilities in the future of prosthetics.

Get this woman an award.

An even thousand

Charlestown Primary School

This is my one thousandth post. Thank you one and all. After a thousand posts, I think I deserve a short break. So for the next couple of days I'm going to re-run some of my archived posts while I take the weekend off. I'll be back with new content bright and early Monday morning.

Thanks again to one and all. It's your feedback, your comments, your e-mail and your good humor that keeps me plugging away. See you Monday.