Gene LaBerge, pers. Carl Cochrane, pers. The calcite of the district is well described by Heyl et al. Type 1 is cloudy, deeply etched crystals colored white, brown, orange-pink or gray. Type 2 calcite is cloudy white to yellow steep scalenohedral xls.. Type 3 calcite forms clear colorless scalenohedra modified by rhombohedrons.
Type 4 forms clear highly modified rhombohedrons. The various types form phantoms, scepters or other overgrowths. Parallel growths of complex rhombohedrons are also found. Inclusions, often of marcasite and pyrite, are common. Individual crystals more than a foot long and enormous clusters of great beauty are found in the mines and dumps. Only a few of the many calcite occurrences in the county can be described below.
Localities listed for Grant County under galena, sphalerite, marcasite and pyrite are also calcite localities. The description of calcite habit under Grant County applies also to Iowa County. His work details 7 distinct habits. Type 1 are rounded white, brown to pink opaque modified scalenohedra up to 5 cm long. Type 2a are light yellow translucent to transparent unmodified scalenohedra which may form overgrowths on Type 1.
Type 2a crystals are corroded and may be up to 15 cm long. Type 2b crystals are essentially unetched and unmodified flat rhombohedra found as cm long in geodes. Type 3 are grayish-white, nearly opaque positive scalenohedra. These can form overgrowths on Types 1 and 2a and can be 18 cm long. These may be in parallel growths and as scepter crystals on Type 3 crystals.
Type 5 crystals form white to greenish white rhombohedron with basal pinacoids. These are usually twinned, with the largest reported twins being 18 cm by 15 cm by 13 cm.
Type 6 crystals are steep white opaque rhombohedrons. Many minor modifying forms are also described by Hobbs. He also remarks on rose-colored massive calcite from this area.
The calcite may be massive, as crested masses or as spherical pink to lavender aggregates of manganoan calcite. The calcite fluoresces a bright red, and is associated with barite, celestine, manganite, hematite and goethite Dickey, , LaBerge, ; Hampel, WSC field notes.
Rhombohedral calcite crystals, from Hazel Green, Wisconsin. Field of view is about 25 cm. The description of calcite habits is the same as described for Grant County.
Only a few of the many calcite occurrences in the county will be described. A concrete slurry can be pumped or hoisted from the ground and poured into forms to produce the structural elements of buildings.
The construction industry is the primary consumer of calcite in the form of limestone and marble. These rocks have been used as dimension stones and in mortar for thousands of years.
Limestone blocks were the primary construction material used in many of the pyramids of Egypt and Latin America. Today, rough and polished limestone and marble are still an important material used in prestige architecture. Modern construction uses calcite in the form of limestone and marble to produce cement and concrete. These materials are easily mixed, transported, and placed in the form of a slurry that will harden into a durable construction material. Concrete is used to make buildings, highways, bridges, walls, and many other structures.
Calcite with cleavage: Transparent calcite from Baxter Springs, Kansas, showing characteristic cleavage. Specimen is approximately four inches 10 centimeters across. Calcite as agrilime: Acid-neutralizing qualities of calcite make finely crushed limestone a preferred material for soil treatment. Calcite as an antacid: The acid-neutralizing ability of calcite is used in medicine. High-purity calcite was used to make these antacid tablets. Calcite has numerous uses as a neutralizer of acids.
For hundreds of years, limestones and marbles have been crushed and spread on fields as an acid-neutralizing soil treatment. They are also heated to produce lime that has a much faster reaction rate in the soil. Calcite is used as an acid neutralizer in the chemical industry. In areas were streams are plagued with acid mine drainage, crushed limestone is dispensed into the streams to neutralize their waters.
Calcium carbonate derived from high-purity limestones or marbles is used in medicine. Mixed with sugar and flavoring, calcium carbonate is made into chewable tablets used in the neutralization of stomach acids. It is also an ingredient in numerous medications used to treat digestive and other ailments.
Sorbents are substances that have the ability to "capture" another substance. Limestone is often treated and used as sorbent material during the burning of fossil fuels. Calcium carbonate reacts with sulfur dioxide and other gases in the combustion emissions, absorbs them, and prevents them from escaping to the atmosphere. Calcite as marble blocks: White marble blocks for monuments or statuary, awaiting transport from a quarry in Portugal.
Marble is an attractive and easily worked rock that has long been used for monuments and sculptures. Its lack of significant porosity allows it to stand up well to freeze-thaw action outdoors, and its low hardness makes it an easy stone to work.
It has been used in projects as large as the pyramids and as small as a figurine. It is widely used as cemetery markers, statues, mantles, benches, stairways, and much more. Calcite as chalk: Calcite in the form of chalk from Dover, England. Specimen is about 4 inches 10 centimeters across.
The best way to learn about minerals is to study with a collection of small specimens that you can handle, examine, and observe their properties.
Inexpensive mineral collections are available in the Geology. In a powdered form, calcite often has an extremely white color. Powdered calcite is often used as a white pigment or "whiting. It is a primary ingredient in whitewash, and it is used as an inert coloring ingredient of paint. It is an essential component of limestones , and occurs in other sedimentary rocks.
It also occurs in metamorphic and igneous rocks, and is common in hydrothermal environments. Calcite is a common vein filling mineral in many rock types.
0コメント