page_title: Yule Marble
section_title: Characteristics
hierarchical_section_title: Yule Marble / Geology / Characteristics
caption_attribution_description: English: Electron image of grains in Yule Marble
context_page_description: Yule Marble is a marble of metamorphosed limestone found only in the Yule Creek Valley, in the West Elk Mountains of Colorado, 2.8 miles southeast of the town of Marble, Colorado. First discovered in 1873, it is quarried underground at an elevation of 9,300 feet above sea level—in contrast to most marble, which is quarried from an open pit and at much lower elevations.
  The localized geology created a marble that is 99.5% pure calcite, with a grain structure that gives a smooth texture, a homogeneous look, and a luminous surface. It is these qualities for which it was selected to clad the exterior of the Lincoln Memorial and a variety of other buildings throughout the United States, in spite of being more expensive than other marbles. The size of the deposits enables large blocks to be quarried, which is why the marble for the Tomb of the Unknowns, with its 56-long-ton die block, was quarried from Yule Marble.
  Yule's quality comes at a high price due to the cost of quarrying in a high-altitude mountain environment.
context_section_description: It is the grain of Yule Marble that gives an appearance of smooth texture, a homogeneous look, and a luminous surface that polishes well. These qualities are why it has been chosen for a number of major national and state landmarks, most notably the Lincoln Memorial. Because of its aesthetic value, architect Henry Bacon successfully urged that it be used to clad the whole exterior of the Memorial, even though it was the most expensive material.
  The overall configuration of the grain is small, irregularly shaped, generally equidimensional to slightly elongated with irregular edges and does not vary significantly among the different grades (in 1992). The edges of the calcite grains are deeply crenulated (irregularly and minutely notched and scalloped). Grain sizes range primarily from 0.1 mm (0.00393 in) to 0.6 mm (0.0236 in), as determined by scanning electron microscope images. There are 2,000–3,000 grains to the square centimeter (0.1550 square inches). Where the marble is in direct contact with the intrusive granite, the most consistent change in the marble is that it becomes extremely coarse-grained, with the grain size in the contact zone being 10 mm to 20 mm (0.3937–0.7874 inches). The grains in turn are tightly bonded in the shape of a jigsaw puzzle, forming crystals which are aligned so that the long axes of the grains are essentially perpendicular to the principal veining in the deposit.
  When marble does break down, the cause is weak boundaries between the grains that permit water or solutions to penetrate into the marble. As water enters, the calcite grains dissolve slightly, and the opening between the grains widens. With time, as the grain openings widen, the edges become smooth, and the grains become rounded. As the surface grains become round, they loosen and fall off the surface of the stone. Because Yule Marble is finely grained with tight bonding, water is not likely to react as quickly as with a coarse-grained, loose-textured marble. Also the crenulated boundaries of Yule Marble crystals may account for the weathering resistance, because the spaces between grains must be widened enough to free adjoining crystals.
  Included in the grains are intrusions (non-calcite material) which does not vary significantly among the four grades; tests in the late 1990s confirm the 1910 amount of 0.5%.  Constant inclusions in all Yules are magnesium oxide (MgO), manganese oxide (MnO), iron oxide (FeO), and strontium oxide (SrO) while other inclusions vary by quarry location. Inclusions are in four groups: quartz (the most abundant and gray in color); muscovite (mica, occurs as thin gold lines and streaks, and also occurs with quartz in clouds of gray mixed with brown); feldspar (with larger grain size 0.591 inches (15 mm) to 1.379 inches (35 mm) and gray in color but less translucent than quartz inclusions); and pyrite. Other minor inclusions are sphene, apatite, rutile, zircon, and sphalerite. An example of inclusion affect is gold veining, the result of iron or manganese, that is still quarried today.
  When the physical characteristics of Yule Marble are compared to the other US marble, the results are about the same for general characteristics of weight, hardness, specific gravity, porosity, absorption, and coefficient of thermal expansion. In strength characteristics, the properties of Yule Marble are lower than most of the other marbles for compressive strength and transverse strength, but they are not unreasonably low. For ordinary uses, stone having a compressive strength of 5,000 lb per square inch is satisfactory.  Test results from 1913 to 1937 ranged from 6,694 to 10,195 pounds per square inch (471 to 717 kg per square cm); in 1996, results were 14,874 (1,046 kg per square cm).
caption: Backscattered electron image of Yule Marble grains
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