Lapis lazuli

Lapis lazuli: It is, known for its vibrant blue colour, has been mined for over 6,000 years, with Afghanistan’s Badakhshan province producing the highest quality.

• About Lapis Lazuli: It is vividly blue rock, sometimes with streaks of gold, used as a semi-precious gemstone.
  • Colour Source: Gets its colour from lazurite (25–40%).

  o Blueness depends on the amount and structure of sulphur in lazurite.

  o Calcite reduces blueness, while the golden sparkle comes from pyrites.

  • Occurrence: Found in Afghanistan, Chile, Russia, and the US.

  o Afghanistan’s Badakhshan province produces the highest quality, mined for over 6,000 years.

  • Historical Significance: Traded to India as early as 1000 BC → found in Mohenjo-daro and Harappa sites of the Indus civilisation → Used by ancient Egyptians for jewellery and as powdered eye shadow → In the Renaissance period, ground into ultramarine pigment for paintings
    • About Lazurite: It is a member of the sodalite group, first described in 1890 from Sar-e-Sang District, Badakhshan, Afghanistan.

    o Occurs almost exclusively in massive form without visible crystals.

    o Optical Properties: Form (Granular, disseminated, or massive; rarely as dodecahedral or cube crystals), Colour (Deep blue), Relief (Low), Interference Colours (Isotropic, sometimes anomalously anisotropic)