1 Mayıs 2013 Çarşamba

Florida State Mineral

Florida State Mineral


One of the most common minerals on earth, calcite composes four to five percent of the Earth’s crust. It is a calcium carbonate that varies greatly in form and color. It is most often white or colorless, but impurities can color it pale shades of gray, yellow, red, green, blue, and even black, brown, or more than one color. These impurities include iron, magnesium, or manganese, and occasionally zinc and cobalt. Calcite readily effervesces in hydrochloric acid and dissolves in most other forms of acid and even in groundwater.
The minerals aragonite and vaterite are polymorphs of calcite, which means all three share the same chemistry but not the same crystal structure. Of these minerals, calcite is the most stable. Calcite sometimes fluoresces, is transparent to opaque, and is birefringent, meaning it displays double refraction. The transparency of Iceland spar, a colorless variety of calcite, makes it useful in the optical field. The most common variety of calcite is a scalenohedron that appears as a double pyramid. A scalenohedron is a crystal of eight or 12 faces, each face being a scalene triangle. This variety is also called the dogtooth spar.
West central Florida has substantial limestone deposits, from Jefferson County south almost to Tampa. Calcite occurs in large clusters underground or underwater in pockets in the limestone. Although calcite is not mined commercially, Florida limestone quarries often unearth some handsome specimens of the mineral. Florida does not have an official state mineral, but calcite represents the state’s geology well.
The word "calcite" comes from the Latin word for lime, calx.
Calcium carbonate, from which calcite is formed, is the principal component of sedimentary rocks, especially limestone. It forms by surface precipitation and groundwater in oceans, lakes, and rivers. Approximately 10 percent of sedimentary rock is limestone. Organic sedimentary rocks are composed of the shells of dead marine organisms.
Calcite also occurs in metamorphic marble, as a vein mineral in deposits from hot springs, and in caverns as stalagmites and stalactites. The mineral may also be found in volcanic and mantle rocks.
Calcite is abundant worldwide. A few notable localities are listed here.
  • Iceland: Helgustadanáma mine, Reydarfjord
  • United Kingdom: Alston Moor, Egremont, and Frizington, Cumbria; Weardale, Durham; and Liskeard, Cornwall; England
  • Germany: St. Andreasberg, Harz Mountains, and Freiberg, Saxony
  • Romania: Herja (Kisbánya), Baia Mare (Nagybánya) district
  • United States: Rossie and Balmat, St. Lawrence County, New York; Hancock, Houghton County, Michigan; Phoenix mine, Keeweenaw County, Michigan; many mines in Reynolds County, Missouri; Joplin, Jasper County, Missouri; Galena, Cherokee County, Kansas; and Picher, Ottawa County, Oklahoma; Elmwood mine, near Carthage, Smith County, Tennessee; Bisbee, Cochise County, Arizona
  • Mexico: Santa Eulalia and Areponapuchic Canyon, Chihuahua; many mines at Guanajuato; Charcas, San Luis Potosí
  • Russia: Dal’negorsk, Primorskiy Krai
  • Namibia: Tsumeb
  • D.R. Congo: Mupine mine, Katanga Province
Calcite is the primary ore of calcium, the main component of chalk, a major constituent of marble, and the base of cements and mortars. Calcite is important in the production of lime and in the manufacture of paint, glass, rubber, fertilizers, and many pharmaceuticals. Calcite has many applications in the chemical and optical fields. Its diversity and beauty make it one of the most collected minerals.
Since calcite is so common, large crystals are not considered very rare. The largest crystal of calcite was reportedly found in Helgustadir, Iceland. It is 23 feet by 23 feet by 6.6 feet (7x7x2 m).
State Mineral
Large Calcite Sample Showing Refractive Properties
State Mineral
Calcite and Fluorite
State Mineral
Orange Calcite and Amethyst
State Mineral
Calcite Crystal on Rock
Group: Carbonate
Chemical Formula: CaCO3
Crystal Structure: Trigonal hexagonal
Hardness (Mohs): 3
Color: Colorless or white, also gray, yellow, green
Transparency: Transparent, translucent
Luster: Vitreous, pearly
Density: 2.7102(2) g/cm3
Streak: White
Cleavage: Perfect on {1011}.
Fracture: Irregular/uneven, step-like
Tenacity: Brittle
Some data courtesy of the Mineralogical Society of America
Author: World Trade Press

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