Iris Quartz

Iris quartz, sometimes also marketed under the name "rainbow quartz" or "anandalite", is a quartz crystal displaying internal spectral colours (single colours or tiny rainbows) under some of the crystal faces (normally the minor rhombohedral faces). These internal colours are interference phenomenon due to reflection and refraction on extremely thin parallel brazil-law twinning lamellae. The quartz crystals themselves are generally colourless or faintly amethystine or citrine, and almost always from vugs in basalt or other trap rock. Such crystals are occasionally facetted, with the rainbow colours displayed as an internal optical phenomenon.

Not to be confused with quartz crystals that show rainbow colours on the surface, rather than internally, because of thin films coating the exterior of the crystal. These are sometimes also sold under the name "rainbow quartz" but obviously can not be cut as gems because the colourful surface film would be lost.

Iris Quartz Gemstones by Colour

This table shows the variety of hues this gemstone can be found in. Click on a photo for more information.
 
General Information
A variety or type of:Quartz
Other Names/Trade Names:
Photos of natural/un-cut material from mindat.org
Further Information
Mineral information:Iris Quartz information at mindat.org
Significant Gem Localities
India
 
  • Madhya Pradesh
Copyright © Jolyon & Katya Ralph 1993-2019. Site Map. Locality, gem & photograph data are the copyright of the individuals who submitted them. For more information please contact the . Gemdat.org is an online information resource dedicated to providing free gemmological information to all.