Light opal

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An opal with pale iridescent colors. Light opals typically have bluish or greenish tones but may also show oranges and pinks. The colors depend on the crystal size within the stone. When the particles are small, some purple can be seen. Medium sized particles diffract green and larger particles show red. Light opals with an opaque, milky background are called white or milk opals. Most light opals come from Australia (Coober Pedy and Mintabie mines).

Synonyms and Related Terms

white opal; milk opal

Other Properties

Massive with no crystalline structure. Cleavage=none Luster = vitreous to pearly. Fracture = conchoidal. Streak = white

Iridescent. Fluoresce=usually white or pale green, some samples phosphoresce

Mohs Hardness 5.5-6.5
Density 2.15
Refractive Index 1.42-1.47

Sources Checked for Data in Record

  • Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
  • Yasukazu Suwa, Gemstones: Quality and Value, Volume 1, Sekai Bunka Publishing Inc., Tokyo, 1999
  • Michael O'Donoghue and Louise Joyner, Identification of Gemstones, Butterworth-Heinemann, Oxford, 2003

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