About the blog: What Things Are Made Of

AMERICA'S GLOBAL DEPENDENCY FOR NEARLY EVERYTHING


The United States relies on imports for dozens of commodities in everyday use. Often enough, that reliance is 100%. In this book I aim to provide awareness of the hidden geology and mineralogy behind common things, and to develop an appreciation for the global resource distribution that underpins our society. While concerns about oil import reliance are in the news every day, our needs for other minerals are comparable and are typically unknown even to technologically aware Americans.





Monday, November 8, 2010

Sandstone facades

Buildings are built of many things. What Things Are Made Of has one chapter about simple home construction and another including monuments and office buildings. I’m involved in planning for the Butte-Silver Bow Courthouse Centennial, coming up in 2012. It’s a huge Beaux-Arts creation whose cost was comparable to that of the Montana State Capitol in Helena.

The first floor fa├žade’s rectangular panels boast uniform, fine-grained gray sandstone. A close look (or better, a careful look from a certain distance) reveals the sandstone’s beds to be angular, curved—not the expected planar laminations. The arrangement is called cross-bedding, crosscutting layering that means the sand was deposited in active rivers. The beds are essentially little sand dunes, channels, and other river-bed forms carved by flowing water.


The sand solidified into sandstone about 78 million years ago near what is now Columbus, Montana. Quarrying there began about 1890. Under the leadership of stonemason Michael Jacobs, born Jacobucci in Italy, the Montana Sandstone Company provided facing stone to numerous buildings in Butte, but it was the contract for the Montana State Capitol that put the company on the map and established Jacobs’ fame and fortune.

Today, stone decorating buildings is called dimension stone, and 78% of that used in U.S. construction is imported, with Brazil, Italy, China, and Turkey supplying nearly equal amounts. Brazil, China, and Italy provide mostly granite and Italy is also a major source of marble. Imported stone was worth $1.5 billion in 2009, compared to $377 million for domestic products. The U.S. is the largest consumer of these materials in the world.