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STAR QUARTZ
Article Id -
AGG0000112
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Nature of Material: quartz is a mineral species; hexagonal (trigonal) Crystal system; chemical composition SiO2
Appearance: Transparent to opaque nearly an colors; also see following entries on Amethyst, Citrine, and Tiger’s-Eye
Phenomena: iridescence, asterism, Aventurescence; also see Tiger-'s-Eye for chatoyant varieties
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Variety and Trade Names
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ROCK CRYSTAL - transparent colorless
SMOKY QUARTZ OR CAIRNGORM - transparent light to dark brown; sometimes nearly opaque black (called Marion)
ROSE QUARTZ- semitransparent to translucent pink, often very light in tone.
AVENTURINE QUARTZ - translucent to opaque quartzite showing glittery reflections (aventurescence) from included crystals of another mineral; most aventurine quartz seen in jewelry is green, although it also occurs in gray. and yellow to brown colors
RUTILATED QUARTZ - see Sagenitic quartz
SAGENITIC QUARTZ (sometimes called Sagenitic) - general term referring to transparent quartz (usual1y rock crystal) containing eye-visible needle-like inclusions, such as golden rutile, or dark tourmaline or actinolite needles; often specified according to the type of inclusions contained – rutilated quartz, Tourmalinated quartz, for example; fanciful desig-nations like Cupid's darts, fleches d'amour, Venus hair stone, Thetis hair stone, and cat's-fur quartz were also applied to Sagenitic quartz.
DUMORTIERITE QUARTZ - translucent to opaque dark blue to violet, colored by Dumortierite inclusions
MILKY QUARTZ - translucent to opaque white to very light gray; also occurs semitransparent with a bluish cast
STAR QUARTZ - rose quartz, or grayish or mill{y quartz showing asterism (generally 6 rays); also called asteriated quartz
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Identification
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Misnomers
Herkimer diamond, Arizona diamond, Arkansas diamond, Alaska diamond, Cornish diamond, etc.
Rock crystal smoky topaz, burnt topaz, Scotch topaz - smoky quartz California lapis - Dumortierite quartz
Moonstone - semitransparent milky quartz
Indian jade - green aventurine quartz
Typical Size Range: 1 - 20 ct; faceted stones over 1000 ct are known
Typical Cutting Styles: faceted, cabochons, carvings, depending on the variety
Identification
Optic Character: DR uniaxial positive or AGG (depending on variety)
Refractive Index: 1.544-1.553 (very constant)
Birefringence: .009 (may not be detectable in aggregate varieties)
Dispersion: .013
Specific Gravity: 2.66 (+ .03. -.02)
Polish Luster: vitreous
Fracture: conchoidal to uneven or granular (in aggregates)
Luster: vitreous
Cleavage: none
Hardness: 7
Toughness: good
Identifying Characteristics
color zoning, twinning, liquid, 2-phase, and 3-phase inclusions, negative crystals, may show bull's-eye or Airy's spiral optic figure. Sagenitic quartz - prominent needle-like inclusions star quartz - contains many tiny inclusions and may have a foil backing to enhance color and star Aventurine quartz - flake or platelet inclusions that cause the aventurescence Dumortierite quartz - strongly pleochroic blue dumortierite inclusions.
Availability: Plentiful to scarce, depending on the variety; quartz is the most common mineral species in the earth's crust. Public Recognition: rock crystal, rose quartz - familiar; smoky quartz - familiar, but frequently confused with topaz; others - unfamiliar
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Birthstone Designation
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Birthstone Designation(s): rock crystal - Monday smoky - November, 1:00 am
Major Source: Brazil. Others: Germany, Hungary, India, Iran, Japan, Madagascar, Mexico, Sri Lanka, South Africa, Scotland, Spain, Switzerland, Uruguay, US, USSR
Recommended Disclosures: Advice when treated or treatment is a possibility.
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The Meaning Of Star Quartz
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HINDI NAME – Star quartz SITARA BILLORE
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