Internet Encyclopedia of Science
GEOLOGY & PLANETARY SCIENCE
A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z

                   • HOME
• ABOUT
• CATEGORIES
• USE OF TEXT AND IMAGES
• NEWSLETTER

  



opal


opal
Opal. Credit: Wikipedia
A cryptocrystalline variety of porous hydrated silica, deposited from aqueous solution in all kinds of rocks, and also formed by replacement of other minerals. Opals are variously colored; the best gem varieties are translucent, with milky or pearly opalescence and iridescence due to light scattering and interference from internal cracks and cavities. Common opal is used as an abrasive, filler, and insulator. Hardness 5.5–6.5; relative density 2.0.


Related category

   • GEOLOGY AND PLANETARY SCIENCE


Also on this site:

Encyclopedia of Alternative Energy & Sustainable Living
Encyclopedia of History


BACK TO TOP