Maine Geology at the Smithsonian Institution
One of the most impressive museum displays of the wonders of geology and world-class minerals is at the Smithsonian Institution's National Museum of Natural History in Washington, DC. Visitors to the Museum are astounded by the diversity of rocks and minerals on display in the Janet Annenberg Hooker Hall of Geology, Gems, and Minerals. Beginning with the primordial solar system, this hall walks the visitor through the processes that formed and continue to transform our planet. From pegmatites bristling with beryl crystals to thick seams of galena, a most remarkable section of the hall is the Mine Gallery where underground mine workings are recreated in striking detail.
Prominently displayed in many sections of the Hall are rocks and minerals from Maine. Many of these specimens are discussed in the following section.
Rocks
Figure 1 |
Figure 1. Collected by Professor Charles V. Guidotti and his students of the University of Maine, this specimen of schist includes large andalusite crystals, a common mineral in the metamorphic rocks of southern Maine. |
Figure 2 |
Figure 2. The uncommonly large black crystals in this specimen of schist are staurolite, also a common metamorphic mineral in southern Maine. They are presented in a groundmass of fine-grained, silvery muscovite mica. |
Figure 3 |
Figure 3. Slate of the variety in this specimen is a common rock type throughout north-central Maine where metamorphic processes were not as intense as in southern Maine. Slate of this type is still quarried for many purposes. |
Geologic Processes
Figure 4 |
Figure 4. Between the Mine Gallery and the Minerals Gallery is a section of the Hall which focuses on geologic processes. Visitors are free to touch and feel the specimens on display here, including this large one of a pothole that was excavated from a coastal setting in Georgetown, Maine. Potholes form over thousands of years by the scouring action of pebbles and cobbles caught in a depression and swirled by water. In this example, a two-foot wide pothole has formed in pegmatite (the rusty colored rock on the right) and schist (the dark layered rock on the left and bottom of the specimen). The fluting on the vertical sides of the specimen are where it was drilled to remove it from the ledge. |
Figure 5 |
Figure 5. This close-up shows the smooth walls of the pothole created by the scour action. The pothole is about 3 feet deep in a specimen that is about 3 feet high and 5 feet across. |
Figure 6 |
Figure 6. This photo shows the site where the pothole was excavated in Georgetown. Note the fluting that resulted from drilling the specimen out. |
Minerals
Figure 7 |
Figure 7. One of the most spectacular specimens discovered at the Newry quarries is this tourmaline dubbed the "Jolly Green Giant." With a girth about equivalent to a soda can and a height of about 8 inches it is certainly one of the most outstanding specimens ever mined in Maine. |
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Figure 8 |
Figure 8. A beautiful slice and gemstone cut from "watermelon" tourmaline collected at Newry. |
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Figure 9 |
Figure 9. This is a flawless aquamarine gemstone cut from a beryl crystal collected at Stoneham.
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Figure 10 |
Figure 10. Amethyst is found at several localities in western Maine. This 3-foot specimen was mined in 1989 in Sweden, Maine. |
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Figure 11 |
Figure 11. Some more common minerals can also be spectacular, like this grossular variety of garnet. The largest crystals in this specimen are about an inch across. |
Text and photos by R. Marvinney except photo number 6 by T. Weddle.
Originally published on the web as the April 2000 Site of the Month.
Last updated on October 6, 2005
