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Properties of Corundum
Corundum is an exceptionally hard and tough material. It is the third-hardest mineral, after diamond and moissanite. It serves as the index mineral for a hardness of nine on the Mohs Hardness Scale. Its hardness, high specific gravity, six-sided crystals and parting are very good diagnostic properties to use in its identification. A summary of the physical properties…
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Made Famous by Rubies and Sapphires
Most people are familiar with corundum; however, very few people know it by its mineral name – instead they know it by the names “ruby” and “sapphire.” A gemstone-quality specimen of corundum with a deep red color is known as a “ruby.” A gemstone-quality corundum with a blue color is called a “sapphire.” Colorless corundum is known…
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Corundum
Corundum has historically been used as an abrasive, but it is most famous as the mineral of ruby and sapphire. What is Corundum? Corundum is a rock-forming mineral that is found in igneous, metamorphic, and sedimentary rocks. It is an aluminum oxide with a chemical composition of Al2O3 and a member of the trigonal crystal system. The mineral is widely known for its extreme hardness and for…
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Why Are Diamonds Found in Arkansas?
The occurrence of diamonds in Arkansas continues to intrigue geologists. About 100 million years ago a deep-source volcanic eruption occurred in this area, bringing material from the mantle rapidly up to the surface. The rising magma was rich in gases that expanded to thousands of times the volume that they occupied while under the enormous…
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Some Not-So-Spectacular “Finds”
The Crater of Diamonds is the only producing diamond mine in the United States, and many people who collect minerals or gemstones would like to own a genuine United States diamond. This patronage of the locality gives a small diamond found at the Park a value that is much higher than a diamond of similar size and…
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Spectacular Diamonds Found At The Park
Although most stones found are small, some spectacular specimens have been found. The “Uncle Sam Diamond,” the largest diamond ever found in North America, was found there in 1924. This pale brown, 40.23 carat stone was found in 1924 by W. O. Bassum. It was cut into an emerald-cut gem weighing 12.42 carats which was…
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Pay-to-Prospect Mining
In the early 1950s the property was opened as a public pay-to-prospect mine, and in 1951 the name was changed to the “Crater of Diamonds.” The State of Arkansas purchased the property in 1972 and began operating it as “Crater of Diamonds State Park.” It is still open year-round as a pay-to-prospect mine visited by…
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Inspiration from Africa
The big diamond rushes in Africa occurred in the late 1800s, and information about the deposits there was widely published. Prior to Huddlestone’s discovery, geologists at the Arkansas State Geological Survey suspected that diamonds might occur in the greenish peridotite soils near Murfreesboro because they were similar to the soils above the African diamond deposits. They did fieldwork…
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Who Discovered Crater of Diamonds?
Diamonds were first discovered at this location in 1906 when John Huddlestone found two strange crystals in the soil of his farm. He didn’t realize that his farm was right above a volcanic pipe filled with lamproite (a volcanic rock formed from partially melted mantle materials which sometimes contains diamond-bearing rocks known as xenoliths that have been…
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Crater of Diamonds State Park
This diamond mine is located near Murfreesboro, Arkansas. For a fee of a few dollars you can enter the mine, search all day and keep any diamonds that you find. In addition to diamonds, you might find one of the many colorful gemstones that occur naturally there. These include: amethyst, agate, jasper, garnet, peridot, hematite and many others. The diamonds at the Park occur in…