Presidential Stone: Whitest and Prettiest

Although Abraham Lincoln’s birthday was last week, we honor him today, as will I, by looking at the building stone of the Lincoln Memorial.  In January 1913, a federal commission approved architect Henry Bacon’s plan for the monument. In contrast with the  common practice of using a steel infrastructure, Bacon proposed white marble walls, columns, and floors. His preferred stone was the Yule marble from Colorado.  

Lincoln Memorial (From Wikipedia)

First described geologically in 1874, the Yule quarry had only opened in 1904 and few easterners had seen it.  Bacon had visited it in 1912 on a trip west and was impressed both by its beauty and by the large blocks the quarry produced.  One long-time supporter called the Yule the “whitest, prettiest, and all things considered, the best marble.” 

The Yule marble was originally deposited as a fine-grained, limey mud in an open shallow sea 345 million years ago when water covered western Canada and most of the United States.  Geologists call this rock the Leadville Limestone in Colorado.  An intrusion of magma 32 million years ago generated the heat necessary to locally metamorphose the Leadville into marble.

The quarry is located about 30 miles west of Aspen, Colorado, at 9,300 feet above sea level.  It is completely underground.  Workers took the stone out of the side of a mountain through portals and lowered them down to a train,which carried the blocks another 3.5 miles to a mill.  Final cutting and shaping required the largest mill in the world, as each of the 38 columns consisted of  25-ton blocks.

Yule quarry (From Wikipedia)

The contractor completed the shell (a nifty Flash program showing construction) of the monument in October 1917.  World War I prevented a dedication from occurring until Memorial Day, 1922.  Coincidentally, this was the same year that the Yule quarry started back in business after shutting down in 1917; in 1919, it had sold to a junk dealer at a sheriff’s sale.  Still popular, the quarry provided a 56-ton block for the Tomb of the Unknown Soldier in 1931, but then closed again in 1941. One year earlier a major crack had appeared in the massive block. 

Tomb of Unknowns (From Wikipedia)

The quarries remained closed until 1990 and limped along closing again in 1998. Yule marble, however, seems to not fade away easily.  New owners reopened the quarry in 1999. They have continued to struggle but have a new project; they are now looking to replace the Tomb of the Unknown Soldier with a new block of marble. 

Tuscon Gem/Mineral: Tents of Trilobites

If ammonites rule in Tucson, then trilobites run a close second. Again, you can buy them by the bag, as jewelry, in slabs, on plates, and even one at a time. At the lowest end, you spend as little as a two bucks, for the hundreds and hundreds of less-than-an-inch-long trilobites from Morocco. For big spenders, there are the one-of-kind crustaceans that will cost several thousand dollars, including a pea-sized one for $700. And, of course, nearly every seller is willing to make you a special deal.
A seven foot wide panel
As usual you get what you pay for, noted one high end dealer, who disdained the cheap trilobites from Morocco. Some of these spectacular trilobites seem almost too perfect to be real. The specimens have heavy ornamentation with spines and tails so fragile that they look as if they would break if you touch them. And in many cases they did break. The guy preparing the fossil simply collected them and glued them back in place, or he may also have made a new appendage with resin.

Did these two really die together?

Some of my favorites are where various species are cemented together to make it look like all lived in harmony. If you are interested, there are several good web sites on how to detect fakes. A nice, non-commercial one is from trilobites.com. But if you don’t care and just want a nice looking trilobite Tucson is the place to come.


Mom and the kids?