Despite not meeting the aspirations of some, Smith Tower does sport a rather handsome lobby. Two stones dominate, onyx marble from Mexico and marble from Alaska. This post will focus on the Mexican rock.
Onyx is a notoriously confusing stone. True onyx is a variety of quartz. It is sometimes referred to as layered chalcedony or black-and-white agate. The onyx used as building stone is not made of quartz but of calcite and is known as onyx marble. Because such calcareous onyx became popular in the United States through stone quarried near Mexico City, it is also called Mexican onyx, as well, no matter its point of origin. Onyx marble used in ancient Rome and by early Egyptians usually came from Algeria. All onyx marble is popular because of the colorful layering and ability to be highly polished. Color variation depends on the amount of iron and manganese and their oxidation states in the deposits, which become layered as they accumulate in pools.
The Smith Tower onyx panels are from Baja California from an area known as El Marmol. Like all onyx marble, it formed layer by thin layer in springs, in this case cold water springs. Other onyx marbles form in hot springs, too. They can also form as stalactites and stalactites. First quarried around 1893, the El Marmol deposits are about 160 miles southeast of Ensenada and 15 miles from the east coast of the peninsula. (One additional note. After posting this blog, I was reminded that the onyx in Smith Tower is also called Pedrara Onyx, in reference to the company that owned the quarries.)
El Marmol achieved a bit of fame for its onyx marble schoolhouse, which was supposedly the only all onyx place of education in the world. Apparently the stones were not polished and by at least the 1950s, the weathered stones were drab and brown. As you can see from this modern shot, it’s not in very good shape.
When geologist George Perkins Merrill visited the Baja quarries in the early 1890s he found the deposits quite pleasing. “Nothing can be more fascinating to the lover of the beautiful in stones than this occurrence, where huge blocks of material of almost ideal soundness, with ever varying shades of color and veination lie everywhere exposed in countless numbers…The colors are peculiarly delicate, and there is a wonderful uniformity in quality…The rose color is, so far as my present knowledge goes, quite unique and wonderfully beautiful.”