Chalcedony

Chrysoprase
India
6.86 carats
© gemselect.com

Although in general terms Chalcedony is a fibrous cryptocrystalline variety of Quartz, recent studies have shown that much Chalcedony is a mixture of cryptocrystalline quartz and mog�nite, another silica mineral related to quartz but with a different crystal structure.

Chalcedony is probably named after an ancient town at the Bosporus.

Yellow, orange and red-orange variety of chalcedony from Botswana is known as Citrus Chalcedony.

348 photos

Chalcedony Gemstones by Colour

This table shows the variety of hues this gemstone can be found in. Click on a photo for more information.

Chalcedony Gemstones by Size

This table shows distribution of Chalcedony gemstone sizes that are listed on this site. This can give a good indication as to the general availability of this gemstone in different sizes.

Contributed photos

Lightest:0.17 cts

Heaviest:931.99 cts

Average:26.35 cts

Total photos:340

Do you have a larger Chalcedony? Why not upload a photo?

0.17ct to 93.35ct93.35ct to 186.53ct186.53ct to 279.72ct279.72ct to 372.90ct372.90ct to 466.08ct466.08ct to 559.26ct559.26ct to 652.44ct652.44ct to 745.63ct745.63ct to 838.81ct838.81ct to 931.99ct

General Information

A variety or type of:

Quartz

Varieties/Types:

Agate - A banded variety of Chalcedony.

Iris Agate - An iridescent variety of Agate.

Onyx - A monochromatic Agate with black and white banding.

Sardonyx - A monochromatic Agate with red/brown and either black or white banding.

Binghamite - Chatoyant Chalcedony with fibres of hematite/goethite.

Bloodstone - A dark green/greenish-blue Chalcedony with small red blood-like spots.

Carnelian - A red to orange variety of Chalcedony.

Chrome-Chalcedony - Emerald green Chalcedony, colored by chromium.

Chrysocolla Chalcedony

Chrysoprase - A green Chalcedony coloured by inclusions of Ni minerals.

Dendritic Agate - A chalcedony containing contrasting branching, or dendritic, mineral inclusions.

Moss Agate - A translucent chalcedony containing green strands of chlorite.

Fire Agate - A variety of Agate containing iridescent spheroids of limonite.

Jasper - Jasper is a dense, opaque, microcrystalline variety of Chalcedony.

Dallasite - A variety of Jasper from Vancouver Island, British Columbia, Canada.

Orbicular Jasper - Jasper containing numerous spherical inclusions.

Myrickite

Petrified Wood - A decorative type of fossil wood where the original organic material has been replaced - usually by chalcedony, agate, opal, etc.

Pietersite - Chalcedony with embedded fibers of amphibole minerals, causing chatoyancy.

Sard - A brown to brownish-red translucent variety of Chalcedony.

Chemical Formula

SiO

Arthur Thomas, Gemstones (2009)

Chalcedony Treatments

Routinely dyed, tests limited: look for dye concentration between grain boundaries, in fractures. Transmitted light: may show mosaic-like marking - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 7

Physical Properties of Chalcedony

Mohs Hardness

6.5 to 7

Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)

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Specific Gravity

2.55 to 2.70

Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)

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Cleavage Quality

None

Walter Schumann, Gemstones of the world (2001)

Fracture

Uneven

Walter Schumann, Gemstones of the world (2001) Shell-likeMore from other references

Optical Properties of Chalcedony

Refractive Index

1.530 to 1.543

Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)

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Optical Character

Uniaxial/+

Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)

Birefringence

0.003 to 0.009

Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)

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Pleochroism

Absent

Walter Schumann, Gemstones of the world (2001)

Dispersion

None

Walter Schumann, Gemstones of the world (2001)

Colour

Colour (General)

All colours

Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) Commonly bandedMore from other references

Causes of Colour

Purple, microscopic sugilite inclusions. Purple, color center similar to that found in amethyst. Blue to greenish blue (chrysocolla quartz), microscopic to sub-microscopic inclusions. Green (chrysoprase), microscopic inclusions of nickeliferous clay-like material. Orange to red (carnelian, jasper), submicroscopic to microscopic inclusions of hydrous Fe oxides

W. William Hanneman, Pragmatic Spectroscopy For Gemologists (2011)

Transparency

Translucent,Opaque

Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) Semi-transparent to opaqueMore from other references

Lustre

Waxy

Michael O�Donoghue, Gems, Sixth Edition (2006)

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Fluorescence & other light emissions

Fluorescence (General)

Often yellowish-green

Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)

Crystallography of Chalcedony

Crystal System

Trigonal

Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)

Habit

Fibrous to grained aggregate

Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)

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Geological Environment

Where found:

Chalcedony is deposited in a variety of environments and deposition is commonly at low temperatures. Light-coloured material with no marked banding is often found as a late hydrothermal deposit or an alteration product in acidic to basic igneous rocks, tuffs and breccias. It is
vary common as crusts, as vein and cavity fillings.

Michael O�Donoghue, Gems, Sixth Edition (2006)

Spectrographic Data

Calculated Spectra:

Click spectra for more information

Chrysoprase - Locality: Unknown

Further Information

Mineral information:

Chalcedony information at mindat.org

Significant Gem Localities


Brazil
Rio Grande do Sul	[var: Agate]

Czech Republic
Hradec Králové Region Jičín District Železnice Doubravice Doubravice quarry	[var: Jasper] No reference listed

Madagascar
Sofia Analalava District Ambolobozo Marovato	[var: Jasper] mindat.org

Morocco
Drâa-Tafilalet Region Midelt Province Midelt Cercle Aït Oufella Caïdat Mibladen Aouli	[var: Jasper] mindat.org

Myanmar
Mandalay Region Pyin-Oo-Lwin District Mogok Township Bernardmyo Pyaung Gaung Myasein Taung	[var: Chrysoprase] Ted Themelis (2008) Gems & mines of Mogok
Zalat-taung	[var: Chrysoprase] Ted Themelis (2008) Gems & mines of Mogok
Kyauk-Pyat-That Kabaing (Ka-Pine; Khabine)	Ted Themelis (2008) Gems & mines of Mogok

Netherlands
Gelderland IJssel river	[var: Jasper] mindat.org

Peru
Arequipa Caravelí Province Acarí District	[var: Chrysocolla Chalcedony]
Huancavelica Huancavelica Province Ascencion District Yauricocha Parish Yanacodo	[var: Agate]
Huánuco Huamalíes Province Tantamayo rhodonite occurrence	[var: Jasper]
Ica Pisco Province Humay District Lily Mine	[var: Chrysocolla Chalcedony]
Lima Cañete Province Miraflores jasper occurrence	[var: Jasper]
Puno Jasper occurrence	[var: Jasper]

Poland
Lower Silesian Voivodeship Ząbkowice Śląskie County Gmina Ząbkowice Śląskie	[var: Chrysoprase] Gemstones of the world, Walter Schumann (2001)

Portugal
Beja Mértola Alcaria Ruiva Balança Mine	[var: Jasper] mindat.org

Russia
Orenburg Oblast Orsk Polkovnik Mt	[var: Jasper] Занимательная минералогия, Ферсман А., 1953, стр. 50

Sri Lanka
Sabaragamuwa Province Ratnapura District Ratnapura	[var: Carnelian]

UK
Scotland Angus Montrose Usan Blue Hole	[var: Agate] [Specimen in the Natural History Museum, London]

USA
Arizona Navajo County Holbrook	[var: Petrified Wood] Gemstones of the world, Walter Schumann, 2001, p.148
Petrified Forest Mining District Petrified Forest	[var: Petrified Wood]
California Imperial County Boulder Park Unnamed Gemstone prospect [1]	U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.
Inyo County Amargosa Range Black Mountains Jubilee Pass Unnamed Gemstone occurrence [2]	[var: Jasper] Symons, Henry Heilbronner (1940), Quartz gem stones of California: Rocks & Minerals: 15: 41; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 317.
Kern County Boron	[var: Petrified Wood]
San Diego County San Ysidro Mountains Dulzura Southeast of Dulzura Unnamed gemstone occurrence	Kunz, George Frederick (1906), Precious stones: Mineral Resources U.S., 1905: 1323-1358; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 318.
Santa Clara County bounded by the Santa Cruz Mountains to the west and the Diablo Range to the east Paradise Valley Unspecified Gemstone occurrences [4]	[Jasper var: Orbicular Jasper] Melhase, John (1934), A diversity of many fine minerals available in California for collectors: Oregon Mineralogist: 2(7): 7; Mineralogist, The (1935): 3(3): 34; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 318; www.cst.cmich.edu/users/dietr1rv/jasper.htm
Siskiyou County Bogus Mountain Bogus Mountain gemstone occurrence	[var: Bloodstone] Symons, Henry Heilbronner (1940), Quartz gem stones of California: Rocks & Minerals: 15: 41; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 318.
Klamath Mountains Cinnabar Camp Unnamed Gemstone occurrence [1]	[var: Agate] U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.
Tulare County Ivanhoe Venice Hills Unnamed Semi-precious Gemstone occurrence [1]	[var: Chrysoprase] Tucker, W. Burling (1919), El Dorado, Lassen, Modoc, Tehama, and Tulare Counties: California Mining Bureau. Report 15: 911; MacFall (1951), Gem Hunter's Guide, 1st ed.; Goodwin, Joseph Grant (1958), Mines and mineral resources of Tulare County, California: California Journal of Mines and Geology (Report 54): 54(3): 344; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 318; Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 350, 424.
Tennessee Knob Deer Creek Chrysoprase Mine (Chrysoprase workings; Gemstone occurrence)	[var: Chrysoprase] Kunz, George Frederick (1899), Precious stones: Mineral Resources U.S., 1898: 589; Tucker, W. Burling (1919), Tulare Counties: California Mining Bureau. Report 15: 911; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 318.
Minnesota Crow Wing County Cuyuna North Range	[var: Binghamite] Gemstones of the world, W. Schumann, 2001, p. 204
Montana Lewis and Clark County East Helena Eldorado Bar Eldorado Bar deposit (Eldorado Strip Mine)	E.Ya. Kievlenko (2003) Geology of gems, p. 70
Nevada Humboldt County Virgin Valley	[var: Petrified Wood] Gemstones of the world, Walter Schumann, 2001, p.148
Utah Iron County Unknown Gemstone Occurrence (MRDS - 10090815)	U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.
Juab County Thomas Range Topaz Mountain Unnamed Agate deposit	[var: Agate] U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.

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