Prehnite

Source: Wikipedia, the free encyclopedia.
Prehnite
Specific gravity
2.8–2.95
Optical propertiesBiaxial (+)
Refractive indexnα = 1.611 – 1.632
nβ = 1.615 – 1.642
nγ = 1.632 – 1.665
Birefringenceδ = 0.021 – 0.033
Dispersionweak r > v
Ultraviolet fluorescenceFluorescent, short UV=blue white mild peach, long UV=yellow
References[2][3][4][5][6]

Prehnite is an

specific gravity is 2.80–2.95 and its color varies from light green to yellow, but also colorless,[8] blue, pink or white. In April 2000, rare orange prehnite was discovered in the Kalahari Manganese Fields, South Africa
. Prehnite is mostly translucent, and rarely transparent.

Though not a zeolite, prehnite is found associated with minerals such as datolite, calcite, apophyllite, epidote, stilbite, laumontite, and heulandite in veins and cavities of basaltic rocks, sometimes in granites, syenites, or gneisses. It is an indicator mineral of the prehnite-pumpellyite metamorphic facies.

It was first described in 1788 for an occurrence in the

Eastern Cape Province, South Africa.[4] It was named for Colonel Hendrik Von Prehn (1733–1785), commander of the military forces of the Dutch colony at the Cape of Good Hope from 1768 to 1780.[4]

It is used as a gemstone.[9]

Extensive deposits of gem-quality prehnite occur in the basalt tableland surrounding Wave Hill Station in the central Northern Territory, of Australia.[10]

Gallery

  • Emerald cut prehnite, 1.85 cm × 1.42 cm, 4.6 grams.
    Emerald cut prehnite, 1.85 cm × 1.42 cm, 4.6 grams.
  • Thin plate of pea-green prehnite on which have grown calcites
    Thin plate of pea-green prehnite on which have grown calcites
  • Water green color spheres of crystallized prehnite with minor calcite on basalt
    Water green color spheres of crystallized prehnite with minor calcite on basalt
  • Carved yellow prehnite pendant, 2.4 cm × 1.8 cm, 5.5 grams
    Carved yellow prehnite pendant, 2.4 cm × 1.8 cm, 5.5 grams
  • Pastel-green rosettes of prehnite blades on matrix
    Pastel-green rosettes of prehnite blades on matrix
  • Prehnite nodule fragment, 11.0 cm × 7.0 cm, 338 grams.
    Prehnite nodule fragment, 11.0 cm × 7.0 cm, 338 grams.
  • Sliced prehnite fragment with calcite core, 9.0 cm diameter.
    Sliced prehnite fragment with calcite core, 9.0 cm diameter.
  • A 2 cm prehnite ball of top quality and color
    A 2 cm prehnite ball of top quality and color

See also

Wikimedia Commons has media related to Prehnite.

References

  1. S2CID 235729616
    .
  2. ^ "Mineralienatlas - Fossilienatlas". www.mineralienatlas.de.
  3. ^ "Prehnite Mineral Data". webmineral.com.
  4. ^ a b c http://www.mindat.org/min-3277.html Mindat
  5. ISBN 0-471-80580-7
  6. ^ http://rruff.geo.arizona.edu/doclib/hom/prehnite.pdf Handbook of Mineralogy
  7. ^
    ISBN 9781862392595
    .
  8. ^
    United States National Museum
    . U.S. Government Printing Office. 1902. p. 520.
  9. ^ Tables of Gemstone Identification By Roger Dedeyne, Ivo Quintens, p. 131
  10. ^ "Wave Hill". History; Discoveries. fossicking.nt.gov.au. 2016. Retrieved 2019-07-11.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Prehnite&oldid=1224592292"