An investigation of differences in the durability of the Colorado Yule marble, a widely used building stone.

By Elaine S. McGee.

U.S. GEOLOGICAL SURVEY BULLETIN 2162

Building Stone of the Lincoln Memorial

Abridged and Presented for your Interest and Enjoyment by Martin Cooney

PART 2) QUALITY, GRADE, MINERALOGIC and PHYSICAL CHARACTERISTICS of the MARBLE

U.S. Department of the Interior / U.S. Geological Survey

Colorado Yule Marble — Building Stone of the Lincoln Memorial. Prepared in cooperation with the National Park Service Colorado Yule Marble — Building Stone of the Lincoln Memorial By Elaine S. McGee. U.S. DEPARTMENT OF THE INTERIOR: BRUCE BABBITT, Secretary U.S. GEOLOGICAL SURVEY: CHARLES G. GROAT, Director UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1999. Published in the Eastern Region, Reston, Va. For sale by U.S. Geological Survey Information Services Box 25286, Federal Center Denver, CO 80225 Library of Congress Cataloging in Publication Data. Manuscript approved for publication August 13, 1998.

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QUALITY OF THE MARBLE

By Elaine S. McGee 

The same fine texture as the best grade Italian

Two of the most remarkable characteristics of the Colorado Yule marble deposit are its quality and purity. Lakes reported that the statuary marble from the Colorado Yule deposit has “the same fine texture as the best grade Italian.”

Vanderwilt compared the statuary Yule marble to the Pentelic marble of Greece. Even today, the Colorado Yule statuary marble is praised, and its quality is compared with that of the world-renowned Carrara marble from Italy.

Carrara marble quarry

Praised as fine and pure

The even grain size and lack of inclusions are the reasons the Yule marble is praised as fine and pure. Chemical analyses of the marble confirm its purity and show that it is composed mostly of calcium carbonate (98.8–99.8 weight percent).

Vanderwilt (1937) described the Leadville Limestone as pure calcite marble and reported that metamorphic minerals (that is, noncalcite inclusions) are lacking over large areas.  Although the marble was formed by contact metamorphism, and thus might show different characteristics close to the intrusion that caused the metamorphism, typical contact metamorphic silicate minerals did not form where the “marbleized” Leadville Limestone came into contact with the intrusive granite.

Contact Metamorphism

The intrusive contact exhibits relatively few metamorphic effects. Although the formations near the Treasure Mountain dome were metamorphosed by the intrusion, proximity to the dome probably had less influence on the development of metamorphic minerals than structural and permeability conditions along joints and contacts of various formations.

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; the grain size in the contact zone is 1.0–2.0 cm, whereas the average grain size in the main body of marble is 2.0 mm.

Chert nodules

Impurities in the marble from the Yule quarry and variations in quality are most common along joints in the stone.  Nodules of gray chert and bodies of “lime” are the two main imperfections that have been encountered and that have caused some problems in quarrying the Colorado Yule marble.

Merrill described lenticular masses of a dense structure with a water-blue tint that were unpredictably encountered in quarrying, but he reported that they could be avoided by judicious quarrying.

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GRADES OF THE MARBLE

Names change with time

The most celebrated samples of the Colorado Yule marble are pure white, with no apparent variation in mineral content or in grain size.  However, the Colorado Golden Vein grade of the Yule marble, which contains inclusions that appear as fine lines of golden veining, is also well known.

The Yule marble is classified into grades by the quarry to reflect stone quality and the amount of inclusions in the stone.  Grade names change with time; in 1992, four grades of Yule marble were marketed for use in buildings.  From highest grade to lowest, these are Snowmass Statuary Select (SSS), Snowmass Statuary (SS), Colorado Golden Vein Select (GV select), and Colorado Golden Vein (GV).

Please note: At the time of writing current quarry owners Colorado Stone Quarries have designated the following names to Yule marble as follows:

Calacatta Lincoln, Calacatta Golden, Statuario Colorado, and Aspen Grey.

Calcatta Lincoln

Calcatta Golden

Statuario Colorado

Aspen Grey

Few intrusions, predominantly white

The Snowmass Statuary grades contain very few inclusions and are nearly pure white with an even grain. The Colorado Golden Vein grades are also predominantly white but contain inclusions that occur as thin linear streaks or as clouds of gold-bronze, tan, or gray.

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MINERALOGIC AND PHYSICAL CHARACTERISTICS

Most marbles contain some mineral inclusions

Characteristics of marbles such as their texture, grain size, color, and inclusions influence the quality and the durability of the stone. Although pure-white, even-textured marbles are sought after and praised, most marbles also contain some mineral inclusions within the calcite matrix that give the marble a characteristic appearance.

Merrill (1914) described the pure whiteness and compact crystallization of the Colorado Yule marble, but he also noted the presence of chert bands in the marble and described two types of colored veins: a dark streak that he attributed to original organic matter and a yellow veining that he attributed to penetration of iron or manganese oxide solutions along lines of strain.

Characteristic color

Bain (1936) reported that the veining in the Colorado Yule Golden Vein marble is predominantly quartz with small amounts of iron- and magnesium-bearing amphiboles, the latter giving the veins their characteristic color.  Vanderwilt (1937) listed dolomite, chert, diopside, quartz, sphalerite, and a small amount of fuchsite as inclusions in the Colorado Yule marble.

Many of the reported mineral inclusions in the marble appear to be minor constituents or are constituents of zones of the marble that have not been routinely quarried. An example is fuchsite, which was reported by Merrill (1914) from an occurrence in the cliff face between quarries number 2 and 3.

Samples taken of all four grades of marble

For this study of the Colorado Yule marble, polished thin sections were made from samples of all four grades of the marble, from several pieces of stone previously removed from the Lincoln Memorial, and from a sample collected at the Yule marble quarry dump pile.  More sections were made from the Colorado Golden Vein grade stone than any other in order to observe the largest variety of inclusion phases present in the marble.

The available samples from the Lincoln Memorial were examined and compared with samples currently quarried to look for similarities between older and newer quarried stone. The disaggregated sample from the quarry dump pile was selected because it was a rare crumbly piece; it was examined to see if any characteristics could be identified that explain its lack of durability compared to most typical samples of Yule marble.

Discarded marble is retrieved at the Yule marble quarry, Colorado.

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An investigation of differences in the durability of the Colorado Yule marble, a widely used building stone.

By Elaine S. McGee 

U.S. GEOLOGICAL SURVEY BULLETIN 2162

Building Stone of the Lincoln Memorial

Abridged and Presented for your Interest and Enjoyment by Martin Cooney

PART 2) QUALITY, GRADE, MINERALOGIC and PHYSICAL CHARACTERISTICS of the MARBLE

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The Story of Colorado Yule Marble

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