Orbicular jasper

Orbicular jasper is a variety of jasper which contains variably-colored orbicules or spherical inclusions or zones. In highly silicified rhyolite or tuff, quartz and feldspar crystallize in radial aggregates of needle-like crystals which provide the basis or seed for the orbicular structure seen in this kind of jasper[1]. The material is quite attractive when polished and is used as an ornamental stone or gemstone.

Additional recommended knowledge

Weighing the right way

Daily Sensitivity Test

Better weighing performance in 6 easy steps

Various local or commercial names have been used for the material, such as kinradite, oregonite, owyhee jasper, ocean jasper and poppy-patterned jasper, depending on the source. Poppy-patterned jasper or Poppy jasper is the varietal name for material from Morgan Hill, Santa Clara County, California. The trade name ocean jasper is used for a variety found along the intertidal shores of northeast Madagascar. In Nebraska orbicular jasper is found in altered rhyolite beds noted for a variety of jaspers and related agates.

References

• R. V. Dietrich - Gemrocks
• Mindat with location data
• Agate variety names - University of Nebraska-Lincoln
• USGS - jasper and other volcanic materials from Nebraska