Maryland State Stone
Cockeysville marble is a typically white, medium- to coarse-grained marble formed from metamorphism of limestone and dolostone, frequently with traces of magnesium mica, tremolite, and quartz.
Marble is a hard, massive (of uniform texture), crystalline rock most often derived from limestone. The purest marble is white and may be translucent. Some marble is tinted pink, red, or blue by impurities such as iron oxide, chert, silica, and magnesium inherited from the parent limestone. The swirls and veins common in many varieties of marble also come from such impurities.
A STATE SYMBOL
While Maryland has never designated an official state stone, Cockeysville marble represents the state well because of its fine quality and historic importance. It was the first marble used for monuments in Washington, DC, notably the Washington Monument and the 108 columns in the wings of the Capitol.
The stone is much in evidence in Baltimore; its city hall is faced with the brilliant white stone, and the stone was used in the city’s famous Battle Monument. The doorsteps of Baltimore’s characteristic row houses are often made of the marble, which is still quarried. The Washington Monument in Baltimore was also constructed of Cockeysville marble.
Marble forms when limestone or dolomitic limestone is heated and compressed. The original particles of calcium carbonate (from pure limestone) or calcium magnesium carbonate (from dolomite) making up the parent rock are melted, losing most of their original texture. During cooling, the minerals crystallize. Cockeysville marble is believed to date to the Cambrian–Ordovician periods from regional metamorphism during the formation of Pangaea. According to some sources, it may reach a thickness of 2,000 feet in places.
DISCOVERY AND NAME
The quality of Cockeysville marble was recognized at least by 1811, and by the 1840s it was being extensively quarried. The designation Cockeysville was not given until 1892, for the town of Cockeysville in Baltimore County, Maryland. The town, in turn, was named for the Cockey family, one of the first to settle in the area.
Cockeysville marble occurs in the counties of Baltimore, Carroll, Harford, and Howard, with extensions into the states of Delaware and Pennsylvania. Marble is found all over the world where limestone rocks have been subjected to high temperature and pressure, usually in episodes of mountain building.
In the U.S., marble is quarried in 14 states besides Maryland. In Europe, the largest deposits are in Austria, Scandinavia, and Italy. The Mount Pentelikos quarry region in Greece was for centuries the largest source of marble for buildings and monuments in the eastern Mediterranean.
Apart from its traditional use as the most refined building and monument stone, marble has a variety of applications in many industries. The purest marble, being almost entirely calcium carbonate, is a component of toothpaste and is used to increase the opacity and brightness of paint and paper. In plastics and rubber manufacturing, pulverized marble lends stiffness and impact strength.
The top two-thirds of the Washington Monument are of marble quarried at Cockeysville, while the lower part uses a very slightly different Cockeysville marble from the quarry at nearby Texas, Maryland.
Since ancient times, marble has been selected for the most exalted monuments. The Taj Mahal’s glorious mausoleum is made of marble. Marble facing formerly gleamed from the sides of the Great Pyramid of Khufu (Cheops). The Parthenon, the famed ancient Greek temple to Athena, is one of many Mediterranean monuments made of Pentelic marble. In imperial China, the marble boat, actually a marble pavilion on a lake, was a feature of the finest parks of royalty and the wealthy; the best known is on the grounds of the Summer Palace in Beijing.
Chemical Formula: CaCO3
Hardness (Mohs): 3-4
Specific Gravity: 2.55-2.7
Color: White or lightly colored, usually with dark streaks.
Streak: Not Found
|Author: World Trade Press|