Chalcedony

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Physical & Optical Properties

Mohs Hardness 6.5 – 7.0
Specific Gravity 2.55 – 2.7
Refractive Index 1.53 – 1.543
Crystal System Trigonal
Luster Waxy
Cleavage None
Color various
Birefringence 0.003
Pleochroism Absent

Mohs Hardness

Mohs Hardness: 6.5 – 7.0
1 Soft10 Hard

Crystal System

a a a Trigonal (Rhombohedral) a = b = c, α = β = γ ≠ 90°

Value & Market

Price Tier Moderate ($50-500/ct)

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 6.5 to 7Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references 2.55 to 2.70Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references NoneWalter Schumann, Gemstones of the world (2001) UnevenWalter Schumann, Gemstones of the world (2001) Shell-likeMore from other references 1.530 to 1.543Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references Uniaxial/+Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) 0.003 to 0.009Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references AbsentWalter Schumann, Gemstones of the world (2001) NoneWalter Schumann, Gemstones of the world (2001) All coloursUlrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) Commonly bandedMore from other references 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 oxidesW. William Hanneman, Pragmatic Spectroscopy For Gemologists (2011) Translucent,OpaqueHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) Semi-transparent to opaqueMore from other references WaxyMichael O?Donoghue, Gems, Sixth Edition (2006) More from other references Often yellowish-greenHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) TrigonalUlrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) Fibrous to grained aggregateUlrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) More from other references Chrysoprase - Locality: Unknown Chalcedony information at mindat.org Brazil&nbsp; [var: Agate] Czech Republic&nbsp; [var: Jasper] No reference listed Madagascar&nbsp; [var: Jasper] mindat.org Morocco&nbsp; [var: Jasper] mindat.org Myanmar&nbsp; [var: Chrysoprase] Ted Themelis (2008) Gems & mines of Mogok [var: Chrysoprase] Ted Themelis (2008) Gems & mines of Mogok Ted Themelis (2008) Gems & mines of Mogok Netherlands&nbsp; [var: Jasper] mindat.org Peru&nbsp; [var: Chrysocolla Chalcedony] [var: Agate] [var: Jasper] [var: Chrysocolla Chalcedony] [var: Jasper] [var: Jasper] Poland&nbsp; [var: Chrysoprase] Gemstones of the world, Walter Schumann (2001) Portugal&nbsp; [var: Jasper] mindat.org Russia&nbsp; [var: Jasper] Занимательная минералогия, Ферсман А., 1953, стр. 50 Sri Lanka&nbsp; [var: Carnelian] UK&nbsp; [var: Agate] [Specimen in the Natural History Museum, London] USA&nbsp; [var: Petrified Wood] Gemstones of the world, Walter Schumann, 2001, p.148 [var: Petrified Wood] U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia. [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. [var: Petrified Wood] 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. [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 [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. [var: Agate] U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia. [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. [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. [var: Binghamite] Gemstones of the world, W. Schumann, 2001, p. 204 E.Ya. Kievlenko (2003) Geology of gems, p. 70 [var: Petrified Wood] Gemstones of the world, Walter Schumann, 2001, p.148 U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia. [var: Agate] U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.

About Chalcedony

Chalcedony is a microcrystalline variety of quartz with a fine, uniform texture and waxy to vitreous luster, encompassing a broad range of colors and named sub-varieties including carnelian, chrysoprase, agate, and onyx. Blue chalcedony—particularly the material from Namibia and Turkey—is especially prized for its soft, translucent lavender-blue color and smooth, cloudlike appearance. It forms in a wide variety of geological settings by precipitation from silica-rich fluids and has been used in gemstones and carvings since prehistoric times.

Jewelry Use

Durability 6/10

Science FYI Family

Frequently Asked Questions

What is Chalcedony?
Chalcedony is a microcrystalline variety of quartz with a fine, uniform texture and waxy to vitreous luster, encompassing a broad range of colors and named sub-varieties including carnelian, chrysoprase, agate, and onyx. Blue chalcedony—particularly the material from Namibia and Turkey—is especially
What is the hardness of Chalcedony?
Chalcedony has a Mohs hardness of 6.5 to 7.0, making it moderate for use in jewelry.
What color is Chalcedony?
Chalcedony is primarily Various.
How much does Chalcedony cost?
Chalcedony falls into the Moderate ($50-500/ct) price range. Prices vary based on color, clarity, cut, and origin.
What is the crystal system of Chalcedony?
Chalcedony belongs to the Trigonal crystal system.

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