Gem, Rock, and Mineral Postage Stamps Featuring
Opal


Mineral Name: Opal

Composition: Silicon oxide hydrate

Nomenclature: Named after the ancient name "opalus" or "upala" which means "precious stone" or "gem."

Industrial Uses: Jewelry, gemstones, carvings.

Additional Notes: A variety of the mineral quartz, opal consists of sub-microscopic spheres of amorphous silica (quartz) stacked like cannonballs on the courthouse lawn. Water fills the interstices, creating a three-dimensional diffraction grating. Light, entering the opal, is refracted and defracted by the water-filled voids producing the changing colors for which precious opal is known.



Australia : Scott 560 : 8 cents : 11 Jul 1973

Precious opal (quartz)



Australia : Scott 580 : 9 cents : 16 Oct 1974

[o/p Australia Scott 560]

Precious opal (quartz)



Australia : Scott 1429 : $1.20 : 5 Apr 1995

[holographic]

Light opal (quartz)



Australia : Scott 1430 : $2.50 : 5 Apr 1995

[holographic]

Black opal (quartz)



Central Africa : Scott 1262b : 600 francs : 1998

Opal (quartz)