Light opal
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Description
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
Physical and Chemical Properties
- Massive with no crystalline structure.
- Cleavage=none
- Luster = vitreous to pearly.
- Fracture = conchoidal.
- Streak = white
- Iridescent.
- Fluorescence = usually white or pale green, some samples phosphoresce
| Mohs Hardness | 5.5-6.5 |
|---|---|
| Density | 2.15 g/ml |
| Refractive Index | 1.42-1.47 |
Resources and Citations
- Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
- Wikipedia: http://en.wikipedia.org/wiki/Opal (Accessed Oct. 12, 2005)
- 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