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