BLUE OREGON OPAL
This is a natural untreated parcel of opal with a blue tone from the oregon opal field that has been drilled.
Weight 14.70 cts app
Size 15 x 11 x 5 mm app
Mohs’ Hardness: 5.5 – 6.5
Density: 1.98 – 2.50
Composition: Hydrous silicon dioxide (SiO2· nH2O)
The opals are found in rhyolite geodes (thundereggs) in a perlite that has altered to a pastel colored clay. The geodes that contain gem-quality opal are only about 10% of the total geodes mined and only about 1% of the geodes contain gem-quality opal with play of color. The remaining geodes contain agate, quartz crystals, or common opal. The geodes vary greatly in size, from a few centimeters in diameter to over a meter.