AGS / Geology / General Geology / Facts About Arkansas
Bauxite - State Rock
This rock was formed by the weathering of nepheline syenite under tropical conditions, a process called laterization. It is a type of lithified soil which is relatively low in silica and high in aluminum. Bauxite was discovered in Arkansas before 1900 and was a major source of ore for aluminum metal for some 90 years in Saline and Pulaski Counties. There are many uses for processed bauxite, aside from metal, including abrasives, cement, refractories, and chemicals. Aluminum compounds are essential ingredients in many common household items, including deodorants, antacids, and paper.
Quartz - State Mineral
Quartz is composed of oxygen and silica combined in a ratio of 2: 1. This mineral is hard, durable, weather-resistant, and relatively common. Quartz crystals formed as hot waters percolated through fractured rock in the Ouachita Mountains some 245 million years ago. Chemically pure sources of quartz are in much demand by industry as a source of the raw chemical feedstock for the manufacture of quartz wafers, silicon metal, glass, fused quartz, and optical fiber. Arkansas has the most significant economically valuable deposits of high-quality quartz in the United States.
Diamond - State Gem
Diamonds were first discovered in Arkansas in 1906. Since that time over 100,000 diamonds have been recovered from the site now known as Crater of Diamonds State Park. The average size recovered is about .21 carat. Colors of the diamonds range from white to yellow and brown and the natural crystals are usually rounded. The largest diamond found in Arkansas is The Uncle Sam, found in 1924. This diamond weighed 40.24 carats.
- Oldest known mapped geologic formation (Collier Shale) about 520,000,000 years old
- Oldest known surface rock (an altered igneous body, Saline County) about 1,025,000,000 years old
- Most abundant sediments – sand, clay, silt, gravel, and marl
- Most abundant sedimentary rocks – shale, sandstone, dolostone, limestone, and chert
- Most abundant igneous rock– syenite (resembles granite, but rarely contains quartz)
- In recent years, an average of 44 earthquakes per year are detected in Arkansas. However, from Jan. 12, 1982 to Jan. 12, 1983, a swarm of nearly 20,000 small earthquakes occurred in Faulkner County.
- Fourteen meteorites have been discovered in Arkansas.
- Area – 53,182 square miles, making Arkansas larger than half of the world’s countries
- Highest point – 2,753 feet above sea level (Magazine Mountain)
- Lowest elevation – 54 feet above sea level (Ouachita River at Arkansas/Louisiana state line)
- Eighteen percent of the state (by area) is irrigated land.
- Navigable length of major rivers: Arkansas River – 308 miles, Ouachita River – 128 miles, Mississippi River – 321 miles, and White River – 255 miles
- Arkansas had the 1st diamond mine in the United States and led the nation in the recovery of diamonds for over 50 years. It is the only place where you can find (and keep) a diamond.
- The two largest diamonds discovered in the United States came from Arkansas.
- Arkansas led the nation in the production of barite for over 30 years.
- Arkansas’ annual value of mineral and fossil-fuel production is more than $1,000,000,000.
- Arkansas’ most valuable non-fuel mineral resources, based on annual production (2007 data), are: bromine, crushed stone, cement, and construction sand & gravel, amounting to 92% of hard minerals value.
- Three fossil fuels – natural gas, oil, and coal – are produced in Arkansas today and vast reserves of lignite are essentially untouched.
- As of 2009, there were about 348 oil and 81 gas fields in production in Arkansas.
- In 2009, about 6,000,000 barrels of oil were produced in Arkansas (16,400 barrels per day)
- As of 2009, about 682,000,000 mcf of gas were produced in Arkansas (over 1.86 million mcf per day)
- Deepest well ever drilled in Arkansas – 20,661 feet (a test well for gas/oil in Yell County)
- Rocks and minerals currently produced or recovered in Arkansas: Bauxite, Dolostone, Gypsum, Quartz, Tripoli, Cement rock, Gemstones, Limestone, Sandstone, Sulfur, Tuff, Clays, Glass/Industrial Sand, Novaculite, Slate, Syenite
- Annually, 45 percent of the world’s bromine is produced in Arkansas, with Arkansas being the only U.S. producer (2007 data).
- More bauxite and vanadium ore has been mined in Arkansas than in all other states combined.
- 1st in the production of bromine
- 1st in the production of quartz crystal and lasca
- 1st in the production of novaculite and silica stone
- 1st in the recovery of diamonds
- 3rd in the production of tripoli
- 4th in the production of kaolin
- 5th in the production of crude gypsum
- 6th in the production of common clays
Most current data for 2007, Arkansas Geological Survey, 2010
