Quartz

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The term cat's eye, or chatoyancy, is used to describe a phenomenal optical property in gemstones, in this case quartz gems. The effect, when present, appears as a bright, narrow slit similar to the pupils in the eyes of your favorite feline. This phenomenon is caused by parallel fibrous or needle-like inclusions that interfere with the passage of light throughout the crystal, scattering and reflecting light back to the viewer as a thin line.

Quartz Polished
Quartz Classification
Common Name Quartz
Species Quartz
Quartz Optical Properties
Transparency Semitransparent - Translucent
Refractive Index 1.544-1.553
Tolerance:very constant
Birefringence 0.009
Optic Character Uniaxial
Optic Sign Positive
Polariscope Reaction Aggregate (AGG), Doubly Refractive (DR)
Fluorescence SWUV: Inert
LWUV: Inert
Pleochroism Unobservable
Quartz Characteristic Physical Properties
Hardness 7
Specific Gravity 2.640-2.690 Typical:2.660
Toughness Good
Inclusions Cat's-eye quartz has parallel needle-like inclusions that are typically asbestos or rutile.
Luster Vitreous
Stability Good
Fracture Conchoidal
Cleavage None
Quartz Chemistry & Crystallography
Chemical Name silicon dioxide (aka silica)
Chemical Formula SiO2
Crystal System Trigonal
Chemistry Classification Silicate

Quartz Spectra

Quartz Spectra
QUARTZ -dyed

Color due to red dye. Absorption from 400nm to 600nm

Jewelry Television acknowledges the significant scientific contributions of John S Harris, FGA to the study of gemstone spectra and with deep appreciation to him, acknowledges the use of his images and related notes about gemstones and their spectra in the educational materials on this website.

Countries of Origin

Tanzania, United Republic Of; Afghanistan; Cambodia; Madagascar; Thailand; Mozambique; Pakistan; Korea (the Republic of); Morocco; Unknown; Malawi; China; Russian Federation (the); Brazil; Bulgaria; Nigeria; Nepal; Argentina; United States of America (the); Republic of Kosovo; Sri Lanka; Uruguay; Dominican Republic (the); Zambia; Bolivia (Plurinational State of); India; Spain; Canada; Turkey; Norway; Namibia; Italy; Mexico; South Africa; Australia; Peru; Germany

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Species/Variety

Blue Moon Quartz

This name refers to quartz gems naturally included with a mist of fine dumortierite crystals. These miniscule blue inclusions give colorless quartz a "mysterious" blue sheen.

Blue Moon Quartz Quartz
Blue Moon Quartz Classification
Common Name Blue Moon Quartz
Blue Moon Quartz Optical Properties
Pleochroism None
Blue Moon Quartz Characteristic Physical properties
Inclusions Blue moon quartz has CO2 or H2O inclusions that give it milky appearance.

Plasma

Plasma is the term for a deep green chalcedony that often shows small yellow, red or white spots.

Plasma Quartz
Plasma Classification
Common Name Plasma
Plasma Optical Properties
Dispersion None
Refractive Index 1.535-1.539
Birefringence 0.004
Pleochroism None
Plasma Characteristic Physical properties
Specific Gravity 2.55
Inclusions Plasma is dark green with white or yellowish spots.The stones semi transparent to opaque nature is what separates plasma from other chalcedonies.

Milky Quartz

Milky quartz is a translucent to opaque white to light gray variety of quartz. It is not commonly used as a gemstone, but is commonly sold as mineral specimens.

Milky Quartz Quartz
Milky Quartz Classification
Common Name Milky Quartz
Milky Quartz Characteristic Physical properties
Inclusions CO2 or H2O inclusions in milky quartz give a milky appearance to the stone.

Hawk's-Eye Quartz

Hawks eye quartz is grayish blue in color due to the presence of crocidolite fibers which are intergrown with quartz producing a wavy, chatoyant shimmer. The word chatoyant comes from the French word chatoyer, meaning to shine like a cat's eyes. When the fibers of crocidolite oxidize (a form of alteration due to contact with air), they turn golden brown, producing the related quartz variety, tigers eye.

Hawk's-Eye Quartz Quartz
Hawk's-Eye Quartz Classification
Common Name Hawk's-Eye Quartz
Hawk's-Eye Quartz Optical Properties
Pleochroism None
Hawk's-Eye Quartz Characteristic Physical properties
Inclusions The cat's-eye of the stone will be the same color as the body of the stone and will be easy to see. Hawk's-eye quartz has a wavy, parallel, fibrous structure and the cat's-eye will have a wavy appearance.

Rock Crystal

Rock crystal is colorless quartz. Due to its clarity, rock crystal is the perfect canvas for a myriad of attractive mineral inclusions, including purple fluorite crystals, golden needles of rutile, metallic pyrite cubes, and many others.

Rock Crystal Quartz
Rock Crystal Classification
Common Name Rock Crystal
Rock Crystal Optical Properties
Dispersion Strength: weak fire Value: 0.013
Pleochroism None
Rock Crystal Characteristic Physical properties
Inclusions Opal in matrix is precious opal mixed throughout a brown ironstone, quartzite, rhyolite or basalt host rock. Stones will have a pock marked appearance with little holes when viewed with a 10X loupe.Andamooka matrix opal will have sheets of color broken up by non-opal material and the edges of color will appear serrated. Andamooka matrix opal is often dyed black and will have black color concentrations that can be seen under magnification. Chips on the stones surface might expose the white inner core. Honduras opal has small flecks of opal in matrix that give it a pinfire appearance and it is lighter than other opal.

Creation Classification

Lab Created

Synthetic quartz is created by a process called hydrothermal growth.Hydrothermally grown synthetic gems crystallize slowly out of a solution (a mix of water and dissolved elements) that has been exposed to heat and pressure similar to the conditions on Earth under which the natural gem mineral grows.Synthetic gems have the same chemical, optical, and physical properties of their natural counterparts, but are a more cost-effective alternative to a natural gem.

Lab Created Quartz
Lab Created Classification
Common Name Lab Created
Lab Created Optical Properties
Dispersion Strength: weak fire Value: 0.013
CCF Reaction blue: often appears pinkish
Pleochroism Dichroic, unobservable to moderate, varying shades of body color
Lab Created Characteristic Physical properties
Inclusions Synthetic quartz is usually free of inclusions but some stones may show inclusions that resemble bread crumbs.Other possible inclusions are gas and liquid two phase nail head spicules and stain cracks.Color banding may be observed parallel to a seed plate as well as flame like twinning.The surface may also have a texture resembling cobblestones. Transparent pink quartz is rare in nature and the synthetic variety usually has eye-visible color banding. Unnatural blue color will be seen in blue synthetic quartz.

Optical Phenomena

Cat's Eye

The term cat's eye, or chatoyancy, is used to describe a phenomenal optical property in gemstones, in this case quartz gems. The effect, when present, appears as a bright, narrow slit similar to the pupils in the eyes of your favorite feline. This phenomenon is caused by parallel fibrous or needle-like inclusions that interfere with the passage of light throughout the crystal, scattering and reflecting light back to the viewer as a thin line.

Cat's Eye Quartz
Cat's Eye Classification
Common Name Cat's Eye
Cat's Eye Characteristic Physical properties
Inclusions Cat's-eye quartz has parallel needle-like inclusions that are typically asbestos or rutile.

Iris Quartz

This unique variety of quartz displays phenomenal iridescence.Its beautiful rainbow of color is caused by reflection and refraction of light within the tiny parallel crystal layers within its structure.Fittingly, it is also called "aurora quartz," "iridescent quartz" or "rainbow quartz."

Iris Quartz Quartz
Iris Quartz Classification
Common Name Iris Quartz
Iris Quartz Optical Properties
Dispersion Strength: weak fire Value: 0.013
Pleochroism None
Iris Quartz Characteristic Physical properties
Inclusions Iris quartz may contain liquid, two-phase and three-phase inclusions, negative crystals, minerals, needles, rutile and iron particles.

Star Quartz

Star quartz exhibits the optical phenomenon called asterism, a star-like pattern created on the surface of a gemstone when light encounters parallel fibrous, or needle-like, inclusions within its crystal structure. Light that strikes the inclusions within the gem reflects off of the inclusions, creating a narrow band of light. When two or more intersecting bands appear, a star pattern is formed. Depending on the crystal, the star may have four, six, or even twelve rays.

Star Quartz Quartz
Star Quartz Classification
Common Name Star Quartz
Star Quartz Optical Properties
Fluorescence SWUV: Inert to weak purple
LWUV: Inert to weak purple
Star Quartz Characteristic Physical properties
Inclusions Star quartz will display a six rayed star due to traces of rutile needles. Stones might show color zoning and twinning planes. Stones might contain liquid, 2-phase, 3-phase inclusions, mineral crystals and negative crystals.
Stability Poor

Inclusions

Gold Quartz

The term gold quartz refers to milky quartz that contains native gold inclusions.

Gold Quartz Quartz
Gold Quartz Classification
Common Name Gold Quartz
Gold Quartz Optical Properties
Pleochroism None
Gold Quartz Characteristic Physical properties
Inclusions Gold quartz will have gold inclusions. CO2 or H2O inclusions that give the stone a milky appearance.

Dumortierite In Quartz

Named for the 19th century French paleontologist Eugene Dumortier, dumortierite crystals are intensely colored and extremely scarce, making them highly prized by mineral collectors. Frequently, dumortierite grows as inclusions within quartz, occurring as an abundance of tiny blue specks, so much as to make the gem appear blue. Other dumortierite colors include pink, purple, pink, reddish brown to brown.

Dumortierite In Quartz Quartz
Dumortierite In Quartz Classification
Common Name Dumortierite In Quartz
Dumortierite In Quartz Optical Properties
Pleochroism None
Dumortierite In Quartz Characteristic Physical properties
Inclusions Dumortierite in quartz will contain dumortierite inclusions and might have liquid, two-phase and three-phase inclusions, negative crystals, minerals, needles, rutile and iron particles.

Dendritic Quartz

This agate variety is termed "dendritic" due to its internal collection of dendrites. Dendrites are fern-like inclusions of iron, manganese, or other metallic oxides that create bold patterns within the gem. Typically, dendritic agates are cut into slabs to best exhibit nature's artwork. As you might guess, these pieces are one-of-a-kinds, as no two dendritic patterns are exactly the same. The internal dendrites may appear black, dark gray, brown or green and, in rare instances, even red.

Dendritic Quartz Quartz
Dendritic Quartz Classification
Common Name Dendritic Quartz
Dendritic Quartz Optical Properties
Dispersion Strength: weak fire Value: 0.013
Pleochroism None
Dendritic Quartz Characteristic Physical properties
Inclusions Dendritic quartz will have dendrite inclusions and may contain liquid, two-phase and three-phase inclusions, negative crystals, minerals, needles, rutile and iron particles.

Covellite In Quartz

The mineral covellite, typically indigo blue to dark blue in color, often displays iridescence that is purplish to deep red. When present in quartz, it exhibits a glittering appearance not soon forgotten. Covellite was named in honor of Niccolo Covelli, an Italian mineralogist who discovered the mineral at Mount Vesuvius.

Covellite In Quartz Quartz
Covellite In Quartz Classification
Common Name Covellite In Quartz
Covellite In Quartz Optical Properties
Dispersion Strength: weak fire Value: 0.013
Pleochroism None
Covellite In Quartz Characteristic Physical properties
Inclusions Covellite in quartz will have covellite inclusions and may contain liquid, two-phase and three-phase inclusions, negative crystals, minerals, needles, rutile and iron particles.

Conundrum Quartz

While rock crystal quartz is easily identifiable, conundrum quartz is called so because it contains a mysterious blend of up to 7 different types of mineral inclusions. Looking into this crystal, you may think that you're taking in a view from outer space! These unique gems are a treat to collectors with their varied, sundry mix of mineral inclusions creating a completely different look for each stone. Take a loupe or microscope to these gems, and explore the confounding menagerie within.

Conundrum Quartz Quartz
Conundrum Quartz Classification
Common Name Conundrum Quartz
Conundrum Quartz Optical Properties
Dispersion Strength: weak fire Value: 0.013
Pleochroism None
Conundrum Quartz Characteristic Physical properties
Inclusions Conundrum quartz can contain liquid, two-phase and three-phase inclusions, negative crystals, minerals, needles, rutile, iron particles, cacoxenite, goethite and hematite. Stones will contain multiple mineral inclusions.

Cleavelandite In Quartz

This white lamellar variety of albite forms extremely thin, platy crystals that are only fractions of millimeters to a few millimeters thick.Cleavelandite was named in honor of 19th century American professor of geology and mineralogy, Parker Cleaveland.

Cleavelandite In Quartz Quartz
Cleavelandite In Quartz Classification
Common Name Cleavelandite In Quartz
Cleavelandite In Quartz Optical Properties
Dispersion Strength: weak fire Value: 0.013
Fluorescence SWUV: Inclusions: cherry red or blue
LWUV: Inclusions: White
Pleochroism None
Cleavelandite In Quartz Characteristic Physical properties
Inclusions Cleaveandite in quartz will have cleaveandite inclusions and may contain liquid, two-phase and three-phase inclusions, negative crystals, minerals, needles, rutile, iron particles. The cleaveandite inclusions are typically round and white with snowball like appearance.

Chlorite In Quartz

When chlorite occurs as an inclusion within quartz, it gives the gem a green color and may cause phantom growths, as seen by the ghost-like layers of crystal left behind as the crystal grew in stages.

Chlorite In Quartz Quartz
Chlorite In Quartz Classification
Common Name Chlorite In Quartz
Chlorite In Quartz Optical Properties
Dispersion Strength: weak fire Value: 0.013
Pleochroism None
Chlorite In Quartz Characteristic Physical properties
Inclusions Chlorite in quartz will have chlorite group inclusions and they sometimes will contain liquid, two-phase and three-phase inclusions, negative crystals, minerals, needles, rutile, iron particles.

Brookite In Quartz

Brookite is a polymorph to rutile and anatase, meaning it shares the same chemical properties, but crystallizes differently.It occasionally is found included within quartz as a red to brown colored crystal.

Brookite In Quartz Quartz
Brookite In Quartz Classification
Common Name Brookite In Quartz
Brookite In Quartz Optical Properties
Dispersion Strength: weak fire Value: 0.013
Pleochroism None
Brookite In Quartz Characteristic Physical properties
Inclusions Brookite in quartz will have brookite inclusions and may contain liquid, two-phase and three-phase inclusions, negative crystals, minerals, needles, rutile, iron particles.

Anatase In Quartz

Anatase is a relatively uncommon gemmy form of titanium dioxide that forms very small unique crystals. The name anatase comes from a Greek word meaning "elongation," referencing its elongated crystal form. Anatase is a polymorph to the more common rutile, as well as brookite. We sometimes see long rutile needles shooting through gemstones, but small anatase crystal inclusions is a much rarer occurrence. Like rutile, anatase usually occurs in honey-yellow, brown to reddish brown, black or deep blue colors.

Anatase In Quartz Quartz
Anatase In Quartz Classification
Common Name Anatase In Quartz
Anatase In Quartz Optical Properties
Dispersion Strength: weak fire Value: 0.013
Pleochroism None
Anatase In Quartz Characteristic Physical properties
Inclusions Anatase in quartz will have anatase inclusions and may contain liquid, two-phase and three-phase inclusions, negative crystals, minerals, needles, rutile, iron particles.

Pyrite In Quartz

One of the most unique quartz varieties is a gorgeous crystal quartz that has the mineral pyrite encapsulated within its confines. Small pyrite crystals seem to float weightlessly in this crystal formation, creating an extremely unique appearance.

Pyrite In Quartz Quartz
Pyrite In Quartz Classification
Common Name Pyrite In Quartz
Pyrite In Quartz Optical Properties
Pleochroism None
Pyrite In Quartz Characteristic Physical properties
Inclusions Pyrite in quartz will have pyrite inclusions and may contain liquid, two-phase and three-phase inclusions, negative crystals, minerals, needles, rutile and iron particles.

Positive Quartz

Positive quartz is a name for quartz that has smaller quartz crystal inclusions trapped inside it. Positive quartz is a play on the term "negative crystal," referring to small, crystal-shaped voids within some gems.

Positive Quartz Quartz
Positive Quartz Classification
Common Name Positive Quartz
Positive Quartz Characteristic Physical properties
Inclusions Positive quartz will contain a quartz crystal inclusion and may include liquid, two-phase and three-phase inclusions, negative crystals, minerals, needles, rutile and iron particles.

Petroleum Quartz

The original discovery of these quartz crystals in 2004 was so unusual that it was actually documented in a major industry publication. Each specimen contains three types of inclusions: oil, gas and water. The yellow that you see is petroleum, the gas bubbles are primarily methane and the colorless inclusions are water that was incapable of mixing with another component. Such unique inclusions are exciting enough for rock hounds across the globe, but when you add in the fact that the crystals are doubly terminated like Herkimer quartz, you have a combination of attributes that simply can't be ignored by enthusiasts.

Petroleum Quartz Quartz
Petroleum Quartz Classification
Common Name Petroleum Quartz
Petroleum Quartz Optical Properties
Dispersion Strength: weak fire Value: 0.013
Pleochroism None
Petroleum Quartz Characteristic Physical properties
Inclusions Petroleum quartz will contain petroleum and might contain liquid, two-phase and three-phase inclusions, negative crystals, minerals, needles, rutile and iron particles.

Medusa Quartz

This unusual name refers to equally unusual inclusions within this crystal. Medusa quartz is host to beautiful radial tufts of blue to green gilalite. The umbrella-like formations were named for their uncanny resemblance to the medusa jellyfish.

Medusa Quartz Quartz
Medusa Quartz Classification
Common Name Medusa Quartz
Medusa Quartz Optical Properties
Dispersion Strength: weak fire Value: 0.013
Pleochroism None
Medusa Quartz Characteristic Physical properties
Inclusions Medusa quartz will contain gilalite inclusions and may contain liquid, two-phase and three-phase inclusions, negative crystals, minerals, needles, rutile and iron particles.

Lithiophilite In Quartz

Lithiophilite is a very scarce phosphate mineral. When present in crystal quartz, its pinkish to brown crystals make acolorful display prized by mineral collectors.

Lithiophilite In Quartz Quartz
Lithiophilite In Quartz Classification
Common Name Lithiophilite In Quartz
Lithiophilite In Quartz Optical Properties
Dispersion Strength: weak fire Value: 0.013
Pleochroism None
Lithiophilite In Quartz Characteristic Physical properties
Inclusions Lithiophilite in quartz will have lithiophilite inclusions and may contain liquid, two-phase and three-phase inclusions, negative crystals, minerals, needles, rutile and iron particles.

Strawberry Quartz

Strawberry quartz is so named because it has a sufficient number of red hematite inclusions to cause a perceived pinkish to reddish body color. While red hematite ribbons are the primary inclusions in strawberry quartz, some gems also contain numerous colorless fluid inclusions and negative crystals, which only add to their desirability and collectability. Mother Nature needed no assistance when creating these beauties and all are 100% natural with no enhancements necessary!

Strawberry Quartz Quartz
Strawberry Quartz Classification
Common Name Strawberry Quartz
Strawberry Quartz Optical Properties
Dispersion Strength: weak fire Value: 0.013
Pleochroism None
Strawberry Quartz Characteristic Physical properties
Inclusions Strawberry quartz will contain hematite inclusions and may included liquid, two-phase and three-phase inclusions, negative crystals, minerals, needles, rutile and iron particles.

Sagenitic Quartz

The term "sagenitic" is applied to quartz that contains a radiating mass of needle-like crystal inclusions of other minerals. Such minerals are commonly rutile, tourmaline, actinolite or goethite.While gemstones are usually prized for having no inclusions, sagenitic quartz specimens are treasured for their artistic, one-of-a-kind beauty, which make a beautiful display in a gem collection or jewelry pieces.

Sagenitic Quartz Quartz
Sagenitic Quartz Classification
Common Name Sagenitic Quartz
Sagenitic Quartz Optical Properties
Dispersion Strength: weak fire Value: 0.013
Pleochroism None
Sagenitic Quartz Characteristic Physical properties
Inclusions Sagenitic quartz may contain liquid, two-phase and three-phase inclusions, negative crystals, minerals, needles, rutile, tourmaline, actinolite needles and iron particles.

Enhancement

Goldenite Quartz

This unique gem begins as natural milky quartz, but is then treated to impregnate the stone's surface with a high karatage of gold. This results in a distinctively patterned, one-of-a-kind gem.

Goldenite Quartz Quartz
Goldenite Quartz Classification
Common Name Goldenite Quartz
Goldenite Quartz Optical Properties
Pleochroism None
Goldenite Quartz Characteristic Physical properties
Inclusions CO2 or H2O inclusions that give the stone a milky appearance. Gold foil has been applied to the surface of the stone.

Lemon Quartz

Named for its refreshing and invigorating yellow color, the strong citrus tones of this gem type are an unusual quality in the gemstone world. The radiant beauty of lemon quartz gems is dazzling, particularly when light dancing from its facets and it truly comes to life. The lemon color is most likely caused by iron breaching the color centers of the stone. The difference between citrine and lemon quartz is in their saturation and color tone. Because of their color similarity, many gem dealers do not even separate the two and use the name citrine for all yellow quartz.

Lemon Quartz Quartz
Lemon Quartz Classification
Common Name Lemon Quartz
Lemon Quartz Optical Properties
Dispersion Strength: weak fire Value: 0.013
Pleochroism Dichroic, unobservable or weak, varying shades of body color
Lemon Quartz Characteristic Physical properties
Inclusions Lemon quartz is a type I clarity stone. Color zoning often present in lemon quartz in the form of "tiger stripes" or "zebra stripes". Stones my contain crystals, negative crystals, liquid inclusions, two-phase inclusions and partially healed fractures.

Quench-Crackled Dyed

For a single crystal to be dyed, it must first be fractured. To achieve this, the method of "quench crackling" combines two types of treatment to improve or alter a stone's appearance. The first step requires the rapid heating and cooling of the stone to create fractures in its surface. The second step is the application of colored dye that is infused under pressure. The dye seeps into the cracks of the crystal to distribute the color throughout the gem.

Quench-Crackled Dyed Quartz
Quench-Crackled Dyed Classification
Common Name Quench-Crackled Dyed
Quench-Crackled Dyed Optical Properties
Dispersion Strength: weak fire Value: 0.013
Pleochroism None
Quench-Crackled Dyed Characteristic Physical properties
Inclusions Quench-crackled dyed quartz will have surface reaching fractures with dye concentrations often in a honeycomb pattern. The fractures will have an iridescent appearance.
Stability Fair
Tim Matthews

Author

Tim Matthews

Tim Matthews is President and Chief Executive Officer of Jewelry Television® (JTV), as well as a member of the company's Board of Directors. He oversees and leads all aspects of the company's powerful omni-digital retail platform that uniquely specializes in fine jewelry and gemstones. His passion for business and gemstones has led him to become a recognized expert in the field of gemology. He is a life member of the Gemmological Association of Great Britain (Gem-A) and has earned Gem-A's highest degrees, the Gemmology (FGA) and Diamond (DGA) diplomas. He is also a Graduate Gemologist (GG) of the Gemological Institute of America (GIA) and has also completed GIA's Graduate Diplomas in Diamonds, Colored Stones and Pearls. Under his leadership, JTV has become the leader in the sourcing and selling of color gemstones and jewelry.

This page was created on June 27, 2014.

This page was last edited on October 24, 2019.