Witherite -- October, 2014
Formula: BaCO3
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Witherite belongs in the barium carbonite mineral family. When it crystallizes, it is categorized in the orthorhombic system and almost always twins. It fluoresces light blue under both long and short wave UV light. It is also phosphorescent under short wave UV light. Witherite can be used to harden steel, as well as to make cement, glass, soap, dye, and explosives. In the 18th century, it was used as rat poison. You can find witherite in Great Britain, Austria, U.S (California, Arizona, New York, and Illinois), Canada, and Namibia. It occurs in low temperature hydrothermal veins. The mineral was named after Dr. William Withering, an English physician and mineralogist who first noted the mineral.
Sources: www.wikipedia.org www.mindat.org www.dakotamatrix.com -- Chosen & Written by Adeline Evans --
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Opalized Agate -- November, 2014
Formula: SiO2
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Agate is a member of the quartz family of minerals. Agates are mainly formed in cavities of volcanic rock. This agate has been made into an opal. Opal is formed when water picks up silica, in this case agate, from sandstone, and carries it into cracks and spaces in the Earth. The water then evaporates, leaving behind a deposit. Agate has long been used in the art of hardstone carving, or carving and shaping stones into pieces of art. Agate was given its name sometime between the 4th and 3rd centuries BC, by the Greek philosopher Theophrastus. It was discovered along the shore of the river Achates, in Greece.
Sources: www.wikipedia.org www.agatelady.blogspot.com -- Chosen & Written by Callum Wayman --
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Baryte (Desert Rose) -- December, 2014
Formula: Ba2SO4
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Baryte (sometimes spelled “barite”) is a mineral of barium
sulfate, and it is used as the primary source of elemental barium. It is also
commonly used as a heavy weighting agent for many drilling processes and gas
exploration to counteract well blowouts. In most cases, baryte can be found
white or colorless in a solid solution with the mineral celestine (SrSO4),
which is the main source for elemental strontium. As seen in the picture as
well as our actual sample, baryte can also take a so-called “desert rose”
shape by crystallizing in arid conditions, forming a circular array of flat plates among sand
grains.The sand in the ground mass of the rock can differ depending on the environment
of lithification (often shallow salt basins), and if there are iron oxides
present, a rusty red color will be apparent.
Sources: www.wikipedia.org -- Chosen and Written by Tucker McCord --
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Rhodochrosite -- February, 2015
Formula: MnCO3
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Rhodochrosite is a manganese carbonate mineral. In its (rare) pure form, it is typically a rose-red color, but impure specimens can be shades of pink to pale brown. Rhodochrosite is Argentina's national gemstone, and it was declared Colorado's state mineral in 2002. The Incas believed that rhodochrosite is the blood of their former rulers, turned to stone; therefore it is sometimes called "Rosa del Inca" or "Inca Rose." Its main use is as an ore of manganese, which is a key component of low-cost stainless steel formulations and certain aluminum alloys. Due to its softness and cleavage, it is very difficult to cut, and therefore is rarely found faceted in jewelry. The formation of rhodochrosite usually occurs in fractures and cavities of metamorphic and sedimentary rocks.
Sources: www.geology.com www.mindat.org www.wikipedia.org -- Chosen and Written by Adeline Evans --
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