Binghamite (Cuyuna North Range, Minnesota, USA) on:
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Binghamite (also called silkstone and cuyunite) is a type of Binghamite on Mindat
/ref> The stone occurs near deposits of
Mining in the area uncovered deposits of the stone, but since mining operations were discontinued in the area many years ago the stone has become fairly rare. The stone has areas that are highly
Binghamite (also called silkstone and cuyunite) is a type of agate
Agate () is a common rock formation, consisting of chalcedony and quartz as its primary components, with a wide variety of colors. Agates are primarily formed within volcanic and metamorphic rocks. The ornamental use of agate was common in Ancie ...
found only on the Cuyuna Range
The Cuyuna Range is an inactive iron range to the southwest of the Mesabi Range, largely within Crow Wing County, Minnesota. It lies along a line between Brainerd, Minnesota, and Aitkin, Minnesota. The width ranges from 1 to 10 miles (1.6 to 16 ...
(near Crosby Crosby may refer to:
Places
;Canada
*Crosby, Ontario, part of the township of Rideau Lakes, Ontario
*Crosby, Ontario, a neighbourhood in the city of Markham, Ontario
;England
*Crosby, Cumbria
*Crosby, Lincolnshire
*Crosby, Merseyside
** Crosby (U ...
) in Crow Wing County
Crow Wing County is a County (United States), county in the East Central part of the U.S. state of Minnesota. As of the 2020 United States census, 2020 census, the population was 66,123. Its county seat is Brainerd, Minnesota, Brainerd. The coun ...
, Minnesota
Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the 22nd most populous, with over 5.75 million residents. Minnesota is home to western prairies, now given over to ...
./ref> The stone occurs near deposits of
iron ore
Iron ores are rocks and minerals from which metallic iron can be economically extracted. The ores are usually rich in iron oxides and vary in color from dark grey, bright yellow, or deep purple to rusty red. The iron is usually found in the fo ...
.
Description
Mining in the area uncovered deposits of the stone, but since mining operations were discontinued in the area many years ago the stone has become fairly rare. The stone has areas that are highly chatoyant
In gemology, chatoyancy ( ), or chatoyance or cat's eye effect, is an optical reflectance effect seen in certain gemstones, woods, and carbon fibre. Coined from the French "œil de chat", meaning "cat's eye", chatoyancy arises either from the ...
similar to pietersite or tiger's eye
Tiger's eye (also called tiger eye) is a
chatoyant gemstone that is usually a metamorphic rock with a golden to red-brown colour and a silky lustre. As members of the quartz group, tiger's eye and the related blue-coloured mineral hawk's eye g ...
. It is a variety of quartz
Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical form ...
with fibers of goethite
Goethite (, ) is a mineral of the diaspore group, consisting of iron(III) oxide-hydroxide, specifically the "α" polymorph. It is found in soil and other low-temperature environments such as sediment. Goethite has been well known since ancient t ...
or hematite
Hematite (), also spelled as haematite, is a common iron oxide compound with the formula, Fe2O3 and is widely found in rocks and soils. Hematite crystals belong to the rhombohedral lattice system which is designated the alpha polymorph of . ...
usually in colors of red, gold, and black. The highest quality binghamite compares with pietersite for color and chatoyancy
In gemology, chatoyancy ( ), or chatoyance or cat's eye effect, is an optical reflectance effect seen in certain gemstones, woods, and carbon fibre. Coined from the French "œil de chat", meaning "cat's eye", chatoyancy arises either from the ...
. When the stone's pattern is arranged in parallel bands it is called silkstone. Binghamite is named after William Bingham, a lapidarist
Lapidary (from the Latin ) is the practice of shaping stone, minerals, or gemstones into decorative items such as cabochons, engraved gems (including cameos), and faceted designs. A person who practices lapidary is known as a lapidarist. A lap ...
, who discovered it in 1936.
References
*{{cite book , last= Schumann, first=Walter , title=Gemstones of the World , year=2007 , publisher=Sterling Publishing Company, Inc. , isbn=1-4027-4016-6 Crow Wing County, Minnesota Geology of Minnesota Agates