Pairl

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Pairl
Various pairls
Various pairls
General
Category Carbonate mineral, protein
Formula
(repeatin unit)
Strunz clessification 05.AB
Creestal seestem Orthorhombic[1]
Identification
Colour white, pink, siller, cream, broun, green, blue, black, yellae, orange, gowd, purpie, iridescent
Cleavage None[1]
Fractur Uneven
Mohs scale haurdness 2.5–4.5 [1]
Streak white
Speceefic gravity 2.60–2.85 [1]
Refractive index
  • Common pearl: 1.52-1.66
  • Black pearl: 1.53-1.69[1]
Birefringence 0.156
Pleochroism Absent
Dispersion None
Ultraviolet fluorescence
  • White pairls: light blue tae licht yellae;
  • Yellae an gowden pearls: yellae-green, greenish broun tae dark broun;
  • Black pairls: commonly pink tae orange-reid [2]

A pairl or purl is a haurd object produced within the saft tishie (speceefically the mantle) o a leevin shelled mollusc or anither ainimal, sic as a conulariid. Juist lik the shell o a clam, a pairl is componed o calcium carbonate (mainly aragonite or a mixtur o aragonite an calcite).[3] in minute creestalline form, which haes been depositit in concentric layers.

References[eedit | eedit soorce]

  1. 1.0 1.1 1.2 1.3 1.4 Schumann, Walter (2001). Gemstones of the World. Robert Hale. p. 230. ISBN 0-7198-0301-2. 
  2. Lazzarelli, Herve Nicolas (2010). Blue Chart Gem Identification. p. 8. 
  3. "Pearl". Gemdat.org. Retrieved Aprile 3, 2017.