23 Mart 2013 Cumartesi

Oklahoma State Rock

Oklahoma State Rock

Barite Rose

Barite rose, or rose rock, is a distinctive formation of the mineral barite (BaSO4) aggregated with sand. Barite most frequently crystallizes in flat tabs or plates. In rose rock, sand/barite tabs radiate out from a central point like the petals of a rose. Oklahoma’s barite roses are colored by the local iron-rich sandstone and occur most often in a rusty brown. Sometimes they are actually pink. Although some barite rose specimens must be carefully separated from surrounding sandstone, at other times the rosettes lie exposed on the surface.
Barite, without the addition of sand, ranges in color from clear or white to blue, pale yellow, or various shades of brown. The mineral is lustrous and dense but soft. It is a sulfate of the toxic and highly reactive element barium, but unlike barium, it is insoluble and non-reactive, so it is not classed as toxic. 
Rose rock, while rare in most areas of the world, is relatively abundant in central Oklahoma. It is characteristic of the state for this reason and because of its rusty color, influenced by the region’s famous red rock. It also has a place in local legend that says the rocks are the tears shed by the Cherokees forced to move to Oklahoma on the Trail of Tears.
The unusual form, ease of collection, and local color of barite rosettes have made them popular with rock and mineral collectors. Collectors succeeded in petitioning Oklahoma’s House of Representatives to designate the rose rock as a state symbol in 1968. Oklahoma was thus one of the first states to adopt a state rock. The town of Noble, where rose rocks are often found, is now home to a privately run Rose Rock Museum and an annual Rose Rock Festival.
The word "barite" comes from the Greek βαρύς (barys), meaning "heavy." This is a reference to the density of barite (not of barium, which does not occur naturally in its pure form).
Two hundred and fifty million years ago, a shallow inland sea covered western Oklahoma, with mountains to the east. Over many millennia, as erosion wore down the mountains, rivers draining the western slopes carried sediments to the inland sea. As they accumulated on the seabed, these sediments, rich in iron oxides, formed the state’s red sandstone. Eventually, as the sea gradually withdrew, barite present in the water grew more concentrated until it precipitated out, crystallizing together with iron oxide and silica to form rose rocks. These range from tiny proto-rosettes to huge clusters, the largest ever found weighing half a ton.
Rose rocks are found in association with sandstone outcrops in a band of counties running down the center of Oklahoma: Lincoln, Cleveland, Oklahoma, McLain, and Garvin. Outside of Oklahoma, barite rosettes can be found in Kansas, California, Egypt, and in Hesse, Germany.
While barite rosettes are a curiosity for collectors, barite has several industrial applications. The largest application of barite worldwide is in drilling oil and gas wells, where a slurry of the heavy mineral helps to support the massive drilling head and to protect it from rock chips. Other uses of barite are as an aggregate in cement, to which it lends strength, and in powdered form to increase the brightness of paper, paint, glass, and cosmetics. Barite is given to patients prior to X-ray of the digestive tract because the mineral is opaque to X-rays. Also, barite is used as an ore of barium.
By far the world’s largest producer of barite is China, which sold 3.6 million metric tons in 2007. Large deposits of barite are also found in India, Morocco, Germany, and the United States.
State Rock
Rose Rock (Barite)
State Rock
Close-up of Rose Rock
State Rock
Small Rose Rock Sample
Name: Barite
Chemical Formula: BaSO4
Color: Colorless, white, yellow, orange, red, brown, blue, gray; sometimes multicolored and banded

Author: World Trade Press

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