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What Is Phyllite?
Phyllite is a foliated metamorphic rock that has been subjected to low levels of heat, pressure and chemical activity. It is composed mainly of flake-shaped mica minerals in parallel alignment. The strong parallel alignment of the mica grains allows the rock to be easily split into sheets or slabs. The alignment of the mica grains gives phyllite a reflective sheen…
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Other Uses for Novaculite
AGGREGATE Novaculite is a very durable rock that resists abrasion and is well suited for use as road base, railroad ballast, and rip-rap. Although it works especially well, its use in these applications is avoided. The reason: novaculite is so abrasive on metal that it causes excessive wear on excavating equipment used to mine it,…
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A World-Famous Sharpening Stone
European settlers in the Ouachita region were the second people to mine the Arkansas Novaculite Formation. They valued it for a different reason. They found that novaculite could be used to sharpen metal tools and weapons. They soon began producing sharpening tools and trading them with distant partners. Arkansas “whetstones,” “oil stones,” and “sharpening stones”…
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First Use of Arkansas Novaculite
Native Americans were the first people to mine the Arkansas Novaculite Formation. They noticed its conchoidal fracture and discovered that it could be knapped – just like flint – into projectile points, scrapers, and cutting tools. They mined novaculite, used it to manufacture cutting tools and weapons, and traded the material and products over a broad area.…
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Novaculite Localities
The most famous locality for novaculite is where the Arkansas Novaculite Formation outcrops in the Ouachita Mountains of central Arkansas and southeastern Oklahoma. It is a Devonian to Mississippian-age rock unit that ranges from about 60 feet thick in the northern Ouachitas to about 900 feet thick in the southern Ouachitas. Outcrops of the Arkansas…
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What is Novaculite?
Novaculite is a dense, hard, fine-grained siliceous rock that breaks with a conchoidal fracture. It forms from sediments deposited in marine environments where organisms such as diatoms (single-celled algae that secrete a hard shell composed of silicon dioxide) are abundant in the water. When the diatoms die, their silicon dioxide shells fall to the seafloor. In…
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Uses of Mariposite
Mariposite is most important for being an ore of gold and a source of placer gold. It has been cut as a dimension stone to produce cemetery markers, fireplaces, facing stone and other architectural works. It is a material that can be used where strength and weather resistance are not required. Much mariposite will weather…
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Mariposite Mineral Localities
Use of the name “mariposite” for green micas has also spread across the world. Mindat.org lists numerous mariposite localities in the United States (Alaska, Arizona, California, Colorado, Nevada, Tennessee, Utah, Washington), Austria, Canada, China, France, Ireland, Japan, Papua New Guinea, Spain, Sweden, and Venezuela.
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The Metamorphic Rock Called “Mariposite”
The name “mariposite” is also used for rocks. The rocks contain enough particles of green mica to produce a green color. These rocks are metamorphic, have been altered by hydrothermal activity, and they are usually thought to have a serpentinite protolith. The green mica usually accounts for a small percentage of the rock, with the…
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Is Mariposite a Mineral?
The name “mariposite” has appeared in the geological literature since the late 1800s. “Mariposite” is not the name of a formally recognized mineral. Instead, it is an informal name that has been widely used for various types of mica with a green color. Green micas are often called “mariposite,” which implies that an identification has been…