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.
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
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.
|Photos of natural/un-cut material from mindat.org|
|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 Hardness||7 to 0Gemmological Tables (2004) , More from other references|
|Specific Gravity||2.65Gemmological Tables (2004) , More from other references|
|Cleavage Quality||NoneGemstones (2009) ,|
|Fracture||ConchoidalGems, Sixth Edition (2006) , More from other references|
|Optical Properties of Quartz|
|Refractive Index||1.544 to 1.553Gemmological Tables (2004) , More from other references|
|Optical Character||Uniaxial/+Gemmological Tables (2004) ,|
|Birefringence||0.009Gemmological Tables (2004) , More from other references|
|Pleochroism||Weakly dichroicGemstones (2009) ,|
|Dispersion||0.013Gems, Sixth Edition (2006) , More from other references|
|Colour (General)||Brown, black, colourless, green, pink, violet, white, yellow, orange, purpleGemstones (2009) ,|
|Causes of Colour||Violet to purple (amethyst), O2+→Fe4+ charge transfer, due to irradiation. Blue, inclusions of blue dumortierite or tourmaline. Green ("greened amethyst" or prasiolite, Fe2+. Green (aventurine quartz), chromian mica (fuchsite) inclusions. Greenish yellow, color center. Yellow to orange (citrine), O2-→Fe3+ charge transfer, various Al3+ related color centers. Smokey (smoky quartz), color center related to the Al3+ impunity. Pink (rose quartz), charge transfer between a substitutional Ti4+ and an interstitial Ti3+ unstable color center O- ion bridging between substitutional aluminum and substitutional phosphorus atom; dumortierite inclusions. White (milky quartz), scattering of light by inclusions larger than the visible wavelengths.Pragmatic Spectroscopy For Gemologists (2011) ,|
|Transparency||Transparent,Translucent,OpaqueGemmological Tables (2004) , More from other references|
|Lustre||VitreousGemstones (2009) ,|
|Fluorescence & other light emissions|
|Fluorescence (General)||Shows no fluorescenceGems, Sixth Edition (2006) ,|
|Crystallography of Quartz|
|Crystal System||TrigonalGemmological Tables (2004) , More from other references|
|Habit||PrismaticGems, Sixth Edition (2006) ,|
|Where found:||Quartz occurs in epithermal veins; it is a characteristic mineral of granites and granite pegmatites and is found in sandstones and quartzites. It occurs in hydrothermal metal deposits and in carbonate rocks where it is common.Gems, Sixth Edition (2006) ,|
Click spectra for more information
|Inclusions in Quartz|
|Inclusions: goethite, hematite, etc. liquid- and two-phase inclusions - Gemmological Tables, Ulrich Henn and Claudio C. Milisenda, 2004, p 9|
|Mineral information:||Quartz information at mindat.org|
|Significant Gem Localities|