Crater of Diamonds State Park is a Arkansas state park in Pike County, Arkansas, in the United States. The park has a plowed field which is one of the few diamond-bearing sites accessible to the public. Diamonds have been discovered in the field continuously since 1906, including the graded-perfect Strawn-Wagner Diamond, found in 1990, and the Uncle Sam, found in 1924, which at over 40 carats is the largest diamond ever found in the United States.

The site became a state park in 1972 when the Arkansas Department of Parks and Tourism purchased the site from private owners in Dallas, Texas, which had operated the site as a tourist attraction.

In 1912, Austin Q. Millar and his son Howard Millar rented and bought surrounding Murfreesboro properties, including the Mauney place, and established an ore processing system. For the next seven years, they mined thousands of modest stones. On 13 January 1919, the operation ended after arson burned the entire place.

Geology

The Early Cretaceous Prairie Creek Diatreme outcrops include magmatic lamproite, pyroclastic lamproite where diamonds are recovered, and maar epiclastics. According to Howard and Hanson, "Lamproites form from partially melted mantle at depths exceeding 93 miles. The rising material is forced to the surface in volcanic pipes, bringing with it xenoliths and xenocryst diamonds from the harzburgitic peridotite or eclogite mantle regions where diamond formation is stabilized. In the instance of the Arkansas lamproites, the diamonds are of eclogite host origin."

In 2002, research by geologist Dennis Dunn (Ph.D. dissertation 2002) found that the diamondiferous epiclastic rocks range from olivine lamproite to phlogopite and olivine-rich tuffs. The chemistry of the mantle xenolith created maximum pressures of around 5 GPa and temperatures of 1000 °C for the upper mantle origin of the lamproitic magma.

Recreation

thumb|Pool at Crater of Diamonds State Park

Crater of Diamonds State Park is known for its plowed field on which visitors can hunt for diamonds and other semi-precious gems. On average, two diamonds are found per day by park visitors.

Diamond mine

Crater of Diamonds State Park is situated over an eroded lamproite volcanic pipe. The park is open to the public and, for a small fee, rockhounds and visitors can dig for diamonds and other gemstones. Park visitors find more than 600 diamonds each year of all colors and grades.

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|1924

|Uncle Sam

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|Largest diamond ever discovered in the United States; as of 2022 in the collection of the Smithsonian

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|1956

|Star of Arkansas

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|Winifred Parker

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|1964

|Star of Murfreesboro

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|Largest diamond ever found by a tourist in the Arkansas area; it was valued at $15,000 in 1964.

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|1981

|Star of Shreveport

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|1990

|Strawn-Wagner Diamond

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|white

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|Found by a local resident, graded perfect. In the collection of the park.

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|2015

|Esperanza Diamond

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|Type IIa, D IF

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|Flawless or near flawless. Cut and polished in Arkansas by Mike Botha After cutting and polishing it was to be set by Erica Courtney then auctioned by Heritage Auctions.

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|2024

|Carine Diamond

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|Chocolate

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|Chocolate-colored. Eighth-largest diamond found in the United States. Found by Julien Navas for a wedding ring for his fiancée Carine Eizlini

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See also

  • Kelsey Lake Diamond Mine, defunct similar commercial operation in Colorado
  • National Register of Historic Places listings in Pike County, Arkansas
  • List of diamonds

References

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  • Crater of Diamonds State Park Arkansas State Parks