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Chrysoprase  (variety of Chalcedony - Quartz)
Current inventory:  0 gems
 

Chemistry:  SiO₂ + N  [Silicon Dioxide + Nickel]

Discovery year unknown;   IMA status: Not Valid (trade name).
Chrysoprase is named from the Greek words Chrysos meaning golden and Prase meaning leek, in allusion to the vegetable's green color.

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

Crystal Data

Crystallography:

Trigonal - Trapezohedal

Crystal Habit:

Widely variable; but typically fibrous (Agate, Chalcedony & Chrysoprase)

Twinning:

None (Agate, Chalcedony & Chrysoprase)

Physical Properties

Cleavage:

[0110] Indistinct

Fracture:

Conchoidal

Tenacity:

Brittle

Hardness (Mohs):

7.0

Density:

2.60 - 2.65 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Various shades of Green

Transparency:

Translucent to Transparent

Luster:

Vitreous

Refractive Index:

1.543 - 1.554  Uniaxial ( + )

Birefringence:

0.0090

Dispersion:

0.013 (low)

Pleochroism:

None

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.

Common Impurities:

Iron oxides

Type Locality:

Possibly Australia

Year Discovered:

Unknown

View mineral photos:

Chrysoprase Mineral Photos and Locations

More Information

Mindat.org  (Chrysoprase)
Mindat.org  (Chalcedony)
Mindat.org  (Quartz)
Webmineral.com  (Quartz)

Chrysoprase is a translucent, apple-green variety of Chalcedony which is a type of cryptocrystaline, or fine-grained, Quartz with a fibrous microstructure. Chrysoprase is colored shades of green by the presence of nickel (N). It is always translucent, never fully transparent and usually found as cabochons but may also be faceted. It is a very attractive material with an almost unique color in the gem world. Because of its color and typical source, Chrysoprase has also been called Australian Jade.

Chrysoprase is found mostly in Australia at Nundle, New South Wales and Marlborough, Queensland; but also found in Brazil at Goiás, Central-West Region and Bahia, Northeast Region and Minas Gerais, Southeast Region. Lesser known sources are Szklary, Zabkowice (Frankenstein), Zabkowice District, Lower Silesia, Poland; Kuruman, Northern Cape Province, South Africa; Plomosa Mts, La Paz County, Arizona, USA and Newfane, Windham County, Vermont, USA.
 

  
Chrysoprase gems for sale:

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