October 3, 2011
V is for Verde Antique
This green beauty gob-smacks our favorite geologist.
By Bill Langer
Verd-antique, (verd-an-teek) — etym., viridis (vir’-e-dis), green, and antiquus (an-ti’-qwus), ancient (noun) — ‘Serpentine … of a tint resembling that of the green incrustation on ancient coins.’ From Geology: for teachers, classes, and private students, by Sanborn Tenney, 1860, p. 310.
My wife, Pam, and I occasionally enjoy a stroll through the stone and tile departments of our local home improvement stores and design centers. She likes to dream about remodeling the kitchen in our soon-to-be retirement home across the street from the grandkids in Phoenix. My thoughts, naturally, drift toward the geology of the various stone samples. Many of the stone samples that are on display have been given whimsical names that describe their color, the area where they came from, or other distinctive characteristics. There are the beautiful garnets in the orangish pink, wavy Juparano Columbo, which is a gneiss from India. How about Baltic Brown, a granite from Finland that contains rimmed spheroids, all floating in a dark brown matrix. And rust-colored veins highlight the elegant ivory-colored Crema Marfil, a marble from Alicante, Spain.
But my eyes always seek out Verde Antique marble, not so much for the geology, but because when it comes to pure beauty, it leaves me gob-smacked. Verde antique has every shade of green, from greenish-white to greenish-black, all blended together and swirled throughout with snow white veins. It is this array of colors and patterns that contributes to its incomparable beauty.
Marble is probably the oldest term used for building stone. The ancient Romans used enormous amounts of stone, and marmore — the root word for marble — was used for all hard stones that could be polished. One of the best known marmore in ancient Roman happens to be Lapis Atracius; you guessed it — a classic example of Verde Antique.
Geologically, most Verde Antique is serpentinite — a metamorphosed dark-colored igneous rock. Serpentine usually has the markings of a snake, hence its name. Simply put, a geologist would not classify Verde Antique as a marble (a metamorphosed limestone or dolomite). Nevertheless, in commercial usage, marble commonly refers to any crystalline rock composed predominantly of calcite or dolomite that is capable of taking a polish; because of its historical usage, serpentinite — Verde Antique — is included with marble.
Juparano Columbo, Baltic Brown, and Crema Marfil each come from single geographic areas. However, well established commercial names sometimes are applied to more than one source of rock. Such is the case of Verde Antique. There literally are dozens of green marbles mined around the world and marketed under that moniker. So, while Juparano Columbo from one stone vendor probably will be very similar to Juparano Columbo from any other vendor (natural variations in the stone and the quarry not withstanding), Verde Antique can vary greatly depending on its source.
While most of the green material in Verde Antique is serpentine, the amount of white veining varies; the white accessory minerals in the veins can vary from calcite (calcium carbonate, CaCO3) to quartz (silicon dioxide, SiO2) and/or magnesite (magnesium carbonate, MgCO3). The varieties of Verde Antique with higher amounts of calcite tend to be somewhat softer than those with lower amounts of calcite. Even so, many varieties of Verde Antique have high hardness, excellent durability, low absorption, and high flexural strength. This makes them excellent choices for exterior applications such as adorning building facades and columns and for interior uses such as floors and countertops that welcome guests to hotels, banks, and other commercial establishments.
Oh, and as Pam is quick to point out, for kitchen countertops, too.
Bill Langer is a geologist with the Mineral Resources Team of the U.S. Geological Survey and can be reached at 303-236-1249 or via e-mail at email@example.com.