Field tripping in Arkansas: Diamonds, hot springs, and quartz crystals

Saturday, November 23, 1991

Peter Russell

Map

Arkansas has much to offer the person interested in geology and for family members wishing other forms of attraction.

Little Rock

Arkansas Geological Commission, 3815 W. Roosevelt Road, Zip: 72204. Displays illustrating Arkansas geology. Free brochures available, geological publications and topographic maps sold. Free publication list and state highway map available on request.

Bauxite

Bauxite Museum, P.O. Box 242, Zip: 72011, just off Interstate 30, 32 km south of Little Rock between Benton and Bryant. Historic museum and mineral displays.

At the beginning of the Eocene the shallow sea in the West Gulf Coast Plain started to retreat from southern and eastern Arkansas. Lateritic weathering partly caused the salt spray from the sea was very active in forming bauxite from the weathering of the nepheline syenite intrusions which formed islands at the edge of the basin. Some bauxite was stripped from the islands filling channels between them. Some of the syenite islands were not completely weathered so that the original lateritic sequence may be seen in the bauxite mines.

Hot Springs

Mid-America Museum, 400 Mid-America Park, Zip: 71913. A "hands-on" museum which includes displays of Arkansas minerals.

Hot Springs National Park, Zip: 71901.

Hot Springs National Park is the only national park in Arkansas and the only national park within a city. The park manages 5,000 acres of land surrounding the north end of the City of Hot Sprints. It includes the discharge area of the hot springs and the historical Bathhouse Row. Tours of the Lamar Bathhouse (illustrated) and the thermal features are given. Camp grounds and mountain hiking trails are available in the park.

Mountain Pine

Ouachita Geo-float Trail. U.S. Corps of Engineers, P.O. Box 4, Zip: 71956. Self-guided boat trip on Lake Ouachita to examine the regional geology; free guidebook available (no collecting).

Quartz Crystal Mines

Quartz crystals may be collected at a number of fee-paying mines.

Coleman Crystal Yard and Rock Shop, Star Route 1, Box 160, Jessieville, Arkansas, 71949; (501) 984-5328.

The rock shop where permits and directions to the mine may be obtained, is located 24 km north of Hot Springs on State Highway 7. Fresh material is produced daily, bring your own collecting equipment (remember the safety glasses!). Camping available at the mine. The mine is open year round, from 8:00 a.m.

Wegner Quartz Crystal Mines, P.O. Box 205, Mount Ida, Arkansas, 71957 (501) 867-2309. The collecting area is east of State Highway 27 about 3 km south of Mount Ida. A sign marks the turnoff. Open from 8:00 a.m. Facilities for camping available. Brochure available.

Quartz crystals occur in crystal-lined fracture systems in the Ordovician, Crystal Mountain Sandstone and Blakely formations. Fractures were formed during faulting and folding which shortened the Ouachita Basin sedimentary rocks by as much as 300 km north to south forming a suitable place for the quartz crystals to grow. From late Pennsylvanian times through the Permian, hydrothermal quartz veins grew and were faulted and reformed.

Crater of Diamonds State Park

The State Park at Murfreesboro is the only place in the world where you may try your hand at diamond hunting in a kimberlite pipe. Diamonds are so abundant that a couple of people make a modest living from mining the gravel with hand tools, sieves and pails of water. 50,000 diamonds have been extracted from the park since the discovery of diamonds here in 1906. 11,000 of these were collected since it became a state park. The largest ever found here was the "Uncle Sam" 40.42 carats. The kimberlite was formed during the Cretaceous when nepheline syenite and other alkalic rocks were injected into rocks throughout Arkansas.

To reach the park, take Interstate 30 south to Arkadelphia and follow Arkansas Highway 26 west to Murfreesboro. Follow highway 301 south 4 kilometres to Crater of Diamonds State Park. The kimberlite is intruded into Carboniferous and Cretaceous sediments. One of these sediments is an attractive red jasper conglomerate. Samples of amethyst, agate, quartz, calcite, barite, yellow ground weathered kimberlite and grey kimberlite may also be collected. Sieves and other tools may be rented at the park. Water troughs are available for washing your finds, and advice on techniques and positive identification of your diamond(s) is given by park staff. Camping and motels are available nearby. Return to Murfreesboro and follow highway 27 south to Nashville. A dinosaur trackway collected from a local gypsum mine is on display next to the courthouse. Take highway 4 south to Old Washington State Park … Confederate capital of Arkansas, where the Bowie Knife was invented.

Ozark Plateau

This region is known for its deposits of lead and zinc which were worked from the Civil War until 1965. The rocks of the area range from Cambrian to Pennsylvanian clastic and carbonate rocks. Solution of the carbonate rocks allowed for the deposition of economic deposits of Galena and Saphalerite.

The Rush Creek Mining District was once the most important zinc-producing area in Arkansas. It is found in the area of the Buffalo National River in northwestern Arkansas. The Rush Historic District includes part of the town of Rush and a restored zinc smelter. Specimens may be collected on some of the mine dumps. Take highway 7 north out of Hot Springs to the Buffalo National River.

Eureka Springs

An interesting day may be spent in Eureka Springs which is advertised as "America’s Little Switzerland." The Basin Park Hotel (accommodation available) on Spring Street is built against the side of the mountain so that each of its seven floors is at ground level. The rest of the family will enjoy the attractions of the Branson area north of Eureka Springs. Silver Dollar City is a "Midwestern Williamsburg" and includes a tour of Marvel Cave which was exploited in the 1880’s for bat guano. The Strip in Branson is a 13 mile stretch of Missouri highway 76 which includes over a dozen country music theatres and other tourist attractions.

Lamar bathhouse

References

Rockhounding in Arkansas by David and Sarah Dodson available from The Dodsons, 9115 Hilaro Springs Road, Little Rock, Arkansas 72209. Price $3.00.

Arkansas Issue of Rocks and Minerals Magazine, July-August 1989, Volume 64, Number 4. Single copies are available for $6.50 U.S. each from Rocks and Minerals, 4000 Albermarle Street N.W., Washington, D.C. 20016.

The Ozarks Outdoors, a guide for fishermen, hunters and tourists by Milton D. Rafferty, University of Oklahoma Press, 1985.

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