Herkimer Diamond - Wikipedia

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• 1 Process of formation
• 2 See also
• 3 References
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Appearance move to sidebar hide From Wikipedia, the free encyclopedia Quartz crystals found in New York

Herkimer diamonds are double-terminated quartz crystals discovered within exposed outcrops of dolomite in and around Herkimer County, New York, and the Mohawk River Valley in the US.[1][2] They are not diamonds; the "diamond" in their name is due to both their clarity and well-formed faces. Because the first discovery sites were in the village of Middleville and in the city of Little Falls, respectively, the crystal is also known as a Middleville diamond or a Little Falls diamond.[3]

Herkimer diamonds became widely recognized after workmen discovered them in large quantities while cutting into the Mohawk River Valley dolomite in the late 18th century. Geologists discovered exposed dolomite in Herkimer County outcroppings and began mining there, leading to the "Herkimer diamond" moniker. Double-terminated quartz crystals can be found around the world, but are often labeled "Herkimer diamonds" regardless of origin.

Process of formation

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The geologic history of these crystals began about 500 million years ago in a shallow sea which was receiving sediments from the ancient Adirondack Mountains to the north. The calcium and magnesium carbonate sediments accumulated and lithified to form the dolomite bedrock currently known as the Little Falls Formation and formerly as the Little Falls Dolostone.[4] While buried, cavities were formed by acidic waters forming the vugs in which the quartz crystals formed. While the dolomite unit is Cambrian, the quartz within the vugs is interpreted to have formed during the Carboniferous Period.[5] Waxy organic material, silicon dioxide and pyrite were present as minor constituents of rock made of dolomite and calcite. As sediment buried the rock and temperatures rose, crystals grew in the cavities very slowly, resulting in quartz crystals of exceptional clarity. Inclusions present in these crystals provide clues[further explanation needed] to the origins of the Herkimer diamonds. Found within the inclusions are solids, liquids (salt water or petroleum), gases (most often carbon dioxide), two- and three-phase inclusions, and negative (uniaxial) crystals. A black hydrocarbon is the most common solid inclusion.[6]

See also

[edit]

• Cape May diamonds, another form of quartz referred to as "diamonds"

References

[edit]

1. ^ King, Hobart M. "Herkimer Diamonds". Geology.com. Archived from the original on 2008-09-14. Retrieved 2008-09-10.
2. ^ Pough, Frederick (1960). A Field Guide to Rocks and Minerals. p. 232.
3. ^ ""Herkimer-style" Quartz". Mindat. Archived from the original on 2009-11-23. Retrieved 2024-01-20.
4. ^ Baldwin, Mike (2003-07-11). "Herkimer Diamonds" (PDF). MAGS Explorer. 2 (7): 1–3. Archived (PDF) from the original on 2021-02-27. Retrieved 2017-02-01.
5. ^ Muskatt, H.S.; Tollerton, V.P. Jr. (September 18–20, 1992). "The Little Falls Dolostone (Late Cambrian); stratigraphy and mineralogy". In April, R.H. (ed.). Field trip guidebook. New York State Geological Association Guidebook, annual meeting. Hamilton, NY. pp. 200–215., as quoted in GEOLEX, USGS Archived 2017-08-23 at the Wayback Machine
6. ^ "Hydrocarbon". Herkimer History. Archived from the original on 2020-05-26. Retrieved 2019-11-26.

External links

[edit] Wikimedia Commons has media related to Herkimer diamond.

• Website for the New York State Academy of Mineralogy
• Prospecting for Herkimer Diamonds
• HerkimerHistory.com
• Video of mining for Herkimer Diamonds with a jackhammer
• Book Review: Collector’s Guide to Herkimer Diamonds

v t e Silica minerals
Crystalline	Coesite Cristobalite Keatite Moganite Quartz Seifertite Stishovite Tridymite
Cryptocrystalline	Chalcedony Chert Flint Jasper
Amorphous	Fulgurite Lechatelierite Opal
Miscellaneous	Tiger's eye Aqeeq
Notable varieties	Chalcedony Agate Carnelian Chrome chalcedony Chrysoprase Heliotrope Moss agate Onyx Opal Fiorite Geyserite Quartz Amethyst Ametrine Herkimer diamond Citrine Smoky quartz Shocked quartz Prasiolite Minerals portal

Retrieved from "https://en.wikipedia.org/w/index.php?title=Herkimer_diamond&oldid=1322230016" Categories:

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• Herkimer County, New York

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