23 Mart 2013 Cumartesi

Oklahoma State Mineral

Oklahoma State Mineral

Hematite is a black to silver-gray, brown to reddish brown, or red mineral. The black, silver, and gray varieties are known as specular hematite. Other varieties include rainbow, iron rose, oolitic, tiger iron, martite, and kidney ore.
Hematite is a very common mineral consisting of iron oxide, and is a mineral cousin of common household rust. The red color in rocks such as sandstone, garnet, and spinel is usually due to the presence of some hematite. The mineral is also responsible for the red color of the planet Mars, where it occurs in abundance. Hematite was first identified on Mars by the Thermal Emission Spectrometer (TES), aboard Mars Global Surveyor in 1998.
The hematite sold as magnetic hematite and sometimes used in jewelry is an artificially created magnetic stone and contains no natural hematite.
Although Oklahoma does not have an official mineral, hematite represents the state’s geology well because it is ubiquitous there. Hematite is the mineral that gives much of Oklahoma its red color. Spectacular examples of hematite formations can be seen at several state parks in the western part of the state.
Hematite is the official state mineral of Alabama.
The name hematite is derived from the Greek word αίμα or haema, meaning blood. All varieties of hematite have a rust-red streak. The mineral is sometimes called "bloodstone" by jewelers.
The formation of iron ores is not fully understood. What is known is that they were formed by the chemical precipitation of iron from shallow seas about 1.8-1.6 billion years ago.
Hematite is often found where lakes, mineral hot springs, and other bodies of standing water previously existed. Therefore, its presence on Mars may indicate the presence or former presence of water there. Hematite has also formed in volcanic regions without water.
Hematite is widespread. Locations of some excellent deposits are listed here.
  • Switzerland: Fibbia, St. Gotthard, Uri; Binntal, Valais; Cavradi, Tavetsch, Graübunden; and many other places
  • Romania: Ocna de Fier (Morávicza; Vaskő)
  • United Kingdom: Cleator Moor, Cumbria
  • Italy: Rio Marina, Elba
  • Norway: Kragerøand Hiassen
  • Brazil: Mesa Redonda and Congonhas do Campo, Minas Gerais; Itabira and the Brumado mine, Bahia; and Miguel Burnier, Ouro Prệto
  • South Africa: Kuruman district, Cape Province
  • Algeria: Nador
  • United States: Thomas Range, Juab County, Utah; and Quartzsite, La Paz County, Arizona
Historical and Modern Uses
Hematite has been used to make jewelry for thousands of years. Hematite objects were placed in tombs of the ancient Egyptians.
In ancient times, it was believed that hematite formed on battlefields where soldiers had shed blood.
Crystal healers believe hematite to be a grounding and healing stone, useful for reducing stress, improving mental focus and concentration, and increasing courage and optimism. Because of its name origin in the Greek word for blood and the deep red color of the stone's streak, hematite is associated with blood disorders and is believed to help hemophilia, anemia, heart disease, kidney disease, cardiovascular diseases, menstrual cramps, and nose bleeds.
Hematite is currently mined in the Lake Superior region of the United States, as well as in Brazil, Australia, England, Italy, Mexico, and Canada.
Large ore bodies of hematite are usually of sedimentary origin. The mineral is also found in metamorphic rocks, and occasionally on igneous rocks as a result of volcanic activity. The other principal ore minerals of iron are magnetite, siderite, taconite, and goethite.
State Mineral
State Mineral
Polished Hematite
State Mineral
Hematite Carving of a Bear
State Mineral
Hematite Imparts Red Color to Oklahoma Landscape
Group: Oxide 
Chemical Formula: Fe2O3, α-Fe2O3
Crystal Structure: Trigonal -hexagonal scalenohedral
Hardness (Mohs): 5.5-6.5
Color: Metallic gray to earthy red tones
Transparency: Opaque
Luster: Metallic to dull
Density: 4.9-5.3
Streak: Red to reddish brown
Cleavage: None, but occasionally exhibits rhombohedral and basal parting
Fracture: Uneven
Tenacity: Brittle
Some data courtesy of the Mineralogical Society of America
Author: World Trade Press

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