Quartz

Big Photo

Chrysoprase
India
6.86 carats
© gemselect.com

Quartz (named after a Slavic word for "hard") is the most common mineral found on the surface of the Earth. A significant component of many igneous, metamorphic and sedimentary rocks, this natural form of silicon dioxide is found in an impressive range of varieties and colours.

Quartz Gemstones by Colour

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

Quartz Gemstones by Size

This table shows distribution of Quartz 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:990 cts
Average:24.27 cts
Total photos:1055
Do you have a larger Quartz? Why not upload a photo?
0.17ct to 99.15ct99.15ct to 198.14ct198.14ct to 297.12ct297.12ct to 396.10ct396.10ct to 495.09ct495.09ct to 594.07ct594.07ct to 693.05ct693.05ct to 792.03ct792.03ct to 891.02ct891.02ct to 990.00ct
General Information
Varieties/Types:
Amethyst - A purple variety of Quartz.
Ametrine - A mixture of Amethyst and Citrine in the same crystal.
Aqua Aura - Clear quartz artificially coated with thin layer of metal to turn it iridescent.
Chalcedony - A cryptocrystalline variety of Quartz.
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.
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.
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.
Citrine - A yellow to yellow-orange or yellow-green variety of Quartz.
Iris Quartz - A quartz showing rainbow colours.
Merlinite - Drusy quartz over psilomelane.
Mystic Quartz - Clear cut quartz coated with thin layer of titanium on pavilion.
Prase - Prase is a leek-green variety of Quartz.
Prasiolite - A green variety of Quartz.
Aventurine - A variety of Quartz containing glistening fragments, usually of mica, but sometimes hematite, goethite or chlorite.
Rock Crystal - A transparent colourless variety of Quartz.
Rose Quartz - Pink variety of Quartz.
Rutilated Quartz - A clear Quartz shot through with golden needles of rutile.
Smoky Quartz - Smoky-grey, brown to black variety of Quartz.
Morion - Sometimes synonymous with Smoky quartz, but often reserved for nearly black Smoky quartz.
Tiger's Eye - Chatoyant yellowish-brown variety of Quartz.
Chemical Formula
SiO
 
2
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Synthetic Quartz
All colors, mostly amethyst, citrine, ametrine: colors are usually intense. Standard tests limited: needle-like 2 phase inclusions, dust-like "breadcrumb" planes, whitish wisps. In synthetic quartz, if present, twinning may create a distinctive lfame-like pattern or may be seen as very thin parallel lines showing interference colors with diagnostic striated appearance. Synthetic blue: Chelsea - red. - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 7
Synthetic quartz: mostly untwinned, rarely triangular sectors with interference colours, "bread crumbs", residues of the seed plate - Gemmological Tables, Ulrich Henn and Claudio C. Milisenda, 2004, p 9
Physical Properties of Quartz
Mohs Hardness7
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Specific Gravity2.65
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Cleavage QualityNone
Arthur Thomas, Gemstones (2009)
FractureConchoidal
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Refractive Index1.544 to 1.553
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Optical CharacterUniaxial/+
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
Birefringence0.009
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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PleochroismWeakly dichroic
Arthur Thomas, Gemstones (2009)
Dispersion
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