Laukšpats (Feldspar, Полевые шпаты)

Feldspar is derived from German "Feld"- field and "Spath" - a rock that does not contain ore. There are two main subgroups that produce gems: the potassium feldspars and the plagioclases (a series from calcium to sodium feldspars).

Varieties/Types:

  • Albite - Sodium-rich Feldspar.
  • Andesine - A plagioclase feldspar with an Albite: Anorthite molar ratio ranging from 50:50 to 70:30.
  • Anorthite - Calcium-rich Feldspar.
  • Bytownite - A plagioclase Feldspar with an Albite: Anorthite molar ratio ranging from 10:90 to 30:70.
  • Labradorite - A plagioclase Feldspar with an Albite: Anorthite molar ratio ranging from 30:70 to 50:50.
    • Spectrolite - Trade name for a Labradorite from Finland that shows the spectral colours especially effectively.
  • Microcline - A triclinic Potassium Feldspar.
    • Amazonite - A green to blue-green variety of Microcline.
  • Oligoclase - A plagioclase feldspar with an Albite: Anorthite molar ratio ranging from 90:10 to 70:30.
  • Orthoclase - A monoclinic Potassium Feldspar.
    • Adularia - A gemmy colourless variety of Orthoclase.
    • Moonstone - A variety of Orthoclase that exhibits a strong blue adularescence.
    • Sanidine - A triclinic Potassium Feldspar found in lavas.
  • Sunstone - A Plagioclase Feldspar, which exhibits aventurescence when viewed from certain directions.
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VarietāteLabradorīts[2], Larvikīts[2], Mikroklīns[37], Ortoklāzs[2], Saulesakmens[30], Sodalīts[5]
Krāsa Zaļa[4], Rozā[4][2][35], Tumši pelēka[35], Pelēcīga[35], Pelēka[35][4][2], Oranža[4], Brūna[4][2], Bezkrāsaina[35], Balta[35][4][2]
Svītra Balta[2]
Spīdums Stikla[35][2]
Caurspīdīgums Caurspīdīgs lidz puscaurspīdīgs[35], Duļķains[35]
Cietība 6 - 6,5[2]
Vibrācija 9[4]
Zodiaks Udensvīrs (Aquarius)[4]
Minerālu klase Silikāti, tektosilikāti[2], Silikātu minerāls[4]
Ķīmiskā formula KAlSi3O8 - NaAlSi3O8 - CaAl2Si2O8[2]
Blīvums (g/cm3) 2,6[2]
Atradnes Ķīna[4]