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Quartz Family
Current inventory:  0 gems
 

Quartz Family

Chemistry:  SiO2    [Silicon Dioxide]

Prehistoric Discovery;   IMA status: Valid (pre-IMA; Grandfathered)
The name Quartz is from the German word quarz (of uncertain origin). The word crystal was originally used only for Quartz and is from the Greek word krystallos, meaning ice, because the Greeks thought the gods had created an unnatural frost that froze ice hard forever.

 

Classification

   

   

Mineral Classification:

Oxides

Strunz 8th Ed. ID:

4/D.01-10

Nickel-Strunz 10th Ed. ID:

4.DA.05

 

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
A : With small cations: Silica family

Related to:

Quartz Group. Polymorph of Coesite, Cristobalite, Stishovite and Tridymite.

 

 

Crystal Data

   

   

Crystallography:

Trigonal - Trapezohedal

Crystal Habit:

Widely variable; but typically long prismatic with steep pyramidal terminations, but may be short prismatic to nearly bipyramidal; fibrous (Agate & Chalcedony)

Twinning:

Very common, penetration twins on the Dauphiné law, about [0001], and the Brazil law, with [1120] as contact plane; contact twins on the Japan law, with [1122] as contact plane, may be repeated; and several other laws.

 

 

Physical Properties

   

 

Cleavage:

[0110] Indistinct

Fracture:

Conchoidal

Tenacity:

Brittle, tough when massive

Moh's Hardness:

7.0

Density:

2.60 - 2.65 (g/cm3)

Luminescence:

May be Triboluminescent

Radioactivity:

Not Radioactive

Other:

Piezoelectric and Pyroelectric and may be Triboluminescent

 

 

Optical Properties

   

   

Color:

Colorless, White, Gray, and many shades of violet, purple, yellow, orange, red, brown, pink, green, blue and black

Transparency:

Transparent to nearly Opaque

Luster:

Vitreous, waxy to dull when massive

Refractive Index:

1.543 - 1.554  Uniaxial ( + )

Birefringence:

0.0090

Dispersion:

0.013 (low)

Pleochroism:

Quartz: none; Amethyst: weak; Citrine: weak; Rose Quartz: strong

 

 

Occurances

   

   

Geological Setting:

In hydrothermal veins, epithermal to alpine; characteristic of granites and granite pegmatites; in sandstones and quartzites, less abundant in other rock types; in hydrothermal metal deposits. Common in carbonate rocks; a residual mineral in soils and sediments.

Common Associations:

Calcite, Chlorite, Epidote, Feldspars, Fluorite, Micas, Zeolites, many other species.

Type Locality:

n/a

Year Discovered:

Prehistoric

View mineral photos:

Quartz Mineral Photos and Locations

 

 

More Information

   

   

 

Mindat.org
Webmineral.com

 

 


Quartz is one of the most common minerals on Earth. It is composed of silicon and oxygen, the two most abundant elements in the crust of the Earth. Quartz comes in many colors including purple/violet (Amethyst); yellow and purple (Ametrine); yellow/orange (Citrine); pink (Rose Quartz); brown (Smoky Quartz); green (Prasiolite) and colorless (Rock Crystal). The various colors are due to trace elements added to the basic Silicon Dioxide formula. Quartz also has many attractive and collectable inclusions created by the addition of other minerals such as Actinolite,  Gilalite, Gold, Lepidocrocite, Pyrite,
Rutile, Tourmaline and many others. Quartz catseyes and stars are also available and are created by the presence of fine asbestos or rutile fibers. Quartz gems have been faceted in enormous sizes. The Smithsonian Institute (SI) has a perfect sphere of flawless Burmese Rock Crystal that is 12.75 inch in diameter and weighs 107 pounds. SI also has a 7000 carat faceted Quartz, a 2258 carat Brazilian Citrine, a 4500 carat Smoky Quartz and a 1362 carat Brazilian Amethyst!
 

  
Quartz Family varieties

Adventurine

colorful, but barely translucent, type of Chalcedony
 

Agate

banded or patterned variety of Chalcedony; there are many names given to the various patterns of Agate: Dendritic, Fire, Lace, Moss, Scenic, Shell, Turritella (fossil or silicified shells), etc. Other names are due to the location of origin.
 

Amethyst

colored Quartz; pale lilac (Rose of France), violet, purple, deep purple with red flashes (Siberian)
 

Ametrine

colored Quartz; both yellow and purple colors in zonal patterns
 

Bloodstone

also known as Heliotrope; dark green Plasma with blood-red and orange spots of iron oxides
 

Carnelian

translucent to semiopaque red, orange or brownish type of Chalcedony colored by the presence of iron oxide
 

Cat's Eye

chatoyant due to asbestos or rutile fibers
 

Chalcedony

microcrystalline Quartz; grayish blue, blue, purplish blue
 

Chert

cryptocrystalline Quartz; opaque, dull gray or whitish Chalcedony; very hard
 

Chrysoprase

apple green type of Chalcedonly; colored by presence of nickel
 

Citrine

colored Quartz; pale yellow, yellow, golden yellow, yellow-orange
 

Dinosaur Bone

silicified dinosaur bone; brownish, red, pink, blue, purple, green, orange, etc.
 

Flint

cryptocrystalline Quartz; opaque, dull gray or whitish Chalcedony; very hard
 

Hornstone

flint
 

Jasper

patterned variety of Chalcedony; shades of red, brown, yellow and green; there are many names given to the various patterns of Jasper: Orbicular, Picture, Scenic, etc. Other names are due to the location of origin.
 

Milky Quartz

milky due to many tiny cavities and bubbles filled with CO2 or water; may also contain Gold
 

Moss Agate

a variety of Agate with "mossy" inclusions
 

Onyx

opaque black and white banded type of Chalcedony
 

Plasma

deep green Chalcedony (opaque due to densely packed actinolite crystals)
 

Petrified Wood

colorful Agate that has replaced tree trunks and limbs
 

Prase

green or yellowish green type of Chalcedony
 

Rock Crystal

colorless, white
 

Rose Quartz

pale to deep pink (due to titanium)
 

Sapphire Quartz

blue Quartz
 

Sard

similar to Carnelian but more brownish and more opaque
 

Sardonyx

banded Onyx with red and white layers
 

Smokey Quartz

pale beige, tan, brown, deep brown (Cairngorm), black
 

Tiger Eye

pseudomorph of asbestos
 

 

 

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