Kentucky Agate

Kentucky Agate: State Rock and Mineral Treasure of the Commonwealth

Roland L. McIntosh
Warren H. Anderson
Agate Photography by Lee P. Thomas
Scenic and Microscopic Photography by Warren H. Anderson
Copyright Date: 2013
Pages: 224
https://www.jstor.org/stable/j.ctt46nzmp
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  • Book Info
    Kentucky Agate
    Book Description:

    Among the rarest and most prized minerals, agate is one of the most exquisite examples of nature's artwork. A striking rock that occurs in various shapes and sizes, with a vivid assortment of colors, agates are coveted by collectors and becoming rarer across the globe. Although the Bluegrass State is usually overlooked in the international study of agate, some of the most beautiful and colorful specimens in the world are hidden away in the rugged terrain of eastern Kentucky's scenic Knobs Region.

    Kentucky Agate is the first book to showcase the unique mineral, treasured for its fine grain and vibrant banks of deep, varied colors. Authors Roland L. McIntosh and Warren H. Anderson have collected hundreds of professional color photographs, revealing the beauty and diversity of this sought-after stone. With detailed maps of the region surrounding the city of Irvine, Kentucky, including parts of Estill, Powell, Jackson, Menifee, Madison, and Lee counties, Kentucky Agate reveals locations where agate may be found. Featuring full-color photographs showing aspects of the rock not visible to the naked eye, this book also provides detailed information on the history, geology, chemistry, and formation of the mineral, giving collectors and Kentucky nature enthusiasts a stunning look into the world of agate collection and the hidden story of the breathtaking formation of the official state rock.

    eISBN: 978-0-8131-4275-3
    Subjects: Environmental Science, Geology

Table of Contents

  1. Front Matter
    (pp. [i]-[vi])
  2. Table of Contents
    (pp. [vii]-[viii])
  3. Introduction
    (pp. 1-4)

    Kentucky agates are among the most prized in the world because of their deep and varied colors. This book of photographs was compiled to show the natural beauty of these Kentucky rocks and describe how they form. The geodes containing agate are not easy to find, but hiking the scenic byways of east-central Kentucky is even more rewarding if you can walk away with a prized specimen. Located in the beautiful Knobs Region of east-central Kentucky, the rugged terrain near Irvine, Kentucky, hides a story of the agate’s dynamic formation and the creation of nature’s art.

    Kentucky agate has been...

  4. 1 Types of Agates
    (pp. 5-10)

    An agate is a concretion or nodule of quartz, of the variety chalcedony, which is silicon dioxide. These glasslike round or spherical nodules contain banded, variegated, or mottled coloring achieved by various minerals, and the banding is often reminiscent of the concentric rings of a tree. Agates can be solid or have a geodal center. Agates can range from as small as a marble to as large as a basketball and can be fractured or brecciated (broken up). The internal bands can be translucent or opaque and of a variety of color intensities.

    Names for the various types of agates...

  5. 2 Location
    (pp. 11-18)

    Kentucky agates are found in parts of Estill, Jackson, Lee, Madison, Rockcastle, and Powell counties in east-central Kentucky, along the foothills of the Appalachian Mountains (figure 2). The Estill County seat is Irvine, the largest of the small communities in this part of Kentucky and a host for an annual agate festival called the Mountain Mushroom Festival and Agate Show. The area is rural, heavily forested, and transected by the Kentucky and Red rivers and Station Camp Creek, a major tributary of the Kentucky River. A number of the tributaries of these rivers are sites where many agates have been...

  6. 3 Agate Formation
    (pp. 19-30)

    Agates are rocks composed of fine to microcrystalline quartz. Quartz is a mineral, and the type of quartz found in agates is chalcedony. In agates the microcrystalline chalcedonic quartz tends to be concentrically banded and to contain microscopic fibers and inclusions of various iron oxides that give it its stained or layered, colored appearance. Agates are found in all parts of the world and are formed as a part of the earth’s geologic processes. Most agates form in igneous rocks, and Kentucky agate is one of the rare types of agate that have distinctly formed in sedimentary rocks. Other types...

  7. 4 Geologic Setting
    (pp. 31-38)

    A description of the geology in east-central Kentucky involves a dynamic saga of the earth’s restless movements that occurred millions of years ago. This area is part of the western flank of the Appalachian Basin, which subsided over millions of years by the accumulation of thick sedimentary rock deposits. The area is east of the Cincinnati Arch (figure 6), which is a north-trending structural hinge line that was fairly stable and did not subside as much as the basin. Faulting occurs throughout the basin and the agate areas. The Estill County seat, Irvine (see figure 2), is located along the...

  8. 5 Microscopic Petrography of Kentucky Agate: A Microscopic Look at Agates in Reflected and Transmitted Light
    (pp. 39-48)

    Normally, to an unaided eye, the color bands in Kentucky agate look multicolored, and the hues—whether red, yellow, black, or white—appear to be solid colors. But when the same agates are examined with optical petrography through a powerful microscope, a previously undetected world of iron oxide pellets, globules, and spheres illuminating the bands can be seen to form the various colors. Iron minerals such as hematite and limonite are very common, and their oxidation produces the variance in colors we see in agates.

    The photographs in this section show unique agates and agate banding. The rock samples have...

  9. 6 Kentucky Agate Photographs
    (pp. 49-198)

    The following agates are a sample of nature’s art that come from the mountains of eastern Kentucky. Each agate is unique in its origin, formation, colors, shapes, and textures. These agates are presented so that they may be studied and admired. Part of the enjoyment of inspecting these rocks is examining their color and shape variations and trying to identify their type. This process illuminates the science behind the formation of agates. The authors hope readers enjoy this chapter of agate photographs and gain a new knowledge and appreciation of the earth’s wondrous creations. Captions are not included because they...

  10. 7 Agate Jewelry
    (pp. 199-206)

    Kentucky agate is also made into various types of jewelry. Cabochons are small rounded pieces of agate that are polished and fashioned for use in ornamental jewelry such as pendants, belt buckles, bracelets, tie clasps, earrings, and necklaces. The jewelry shown in figures 26 to 37 was created by various jewelers and craftsmen in Kentucky....

  11. Acknowledgments
    (pp. 207-208)
  12. Select Bibliography
    (pp. 209-212)
  13. Index
    (pp. 213-216)