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Opal — specimen 0750, photo © NMNHS
Opal — specimen 0750, photo © NMNHS

Opalspecimen 0750


North America
USA, Oregon, Malheur County, Lake Owyhee, 43.6248°N 117.23541°W
Opal — specimen 0750, locality map

Weight: 2.11 ct; size: 8.08 | 8.03 | 4.48 mm; shape: rectangle; colour: medium light very strongly greenish blue; slightly greyish; clarity: opaque; cut: excellent; treatment: none.

Clean specimen; design ‘Rectangulum Cab’, excellent cut by Tan Pen.

Other specimens
Opal — specimen 0376Opal — specimen 0417Opal — specimen 0167Opal — specimen 0412Opal — specimen 0211Opal — specimen 0227Opal — specimen 0544Opal — specimen 0722Opal — specimen 0229Opal — specimen 0264Opal — specimen 0461Opal — specimen 0469Opal — specimen 0518Opal — specimen 0713Opal — specimen 0720Opal — specimen 0373Opal — specimen 0557Opal — specimen 0361

More information from ‘Classification’

Regarded as mineral species for historical reasons; not a true mineral in the accepted sense of the word as it is either composed of cristobalite and/or tridymite or of amorphous silica; sedimentary and secondary from the alteration of high silica igneous extrusive rocks. There are specimens of 2610 carats (Arem, 1987: 139).