Geological Society of America

17 D6. Geochemistry (Posters)

Tuesday, 26 March 2019
8:30 AM - 5:45 PM
Big Basin/Kaw Nation Rooms

EXAMINATION OF AN ALTERNATIVE METHOD OF OPAL SYNTHESIS

Paper number: 17-6
Program: Technical Sessions
Time: 8:30 AM – 5:45 PM

Authors

Amanda Key Presenting Author
University of Arkansas- Fort Smith, Fort Smith, AR
Dave P. Mayo
University of Arkansas-Fort Smith, Fort Smith, AR
Maurice P. Testa
University of Arkansas Fort Smith, Fort Smith, AR
Christopher Knubley
University of Arkansas Fort Smith, Fort Smith, AR

Abstract

Opal is a hydrated amorphous form of silica, SiO₂. Water contents can range anywhere from 3% to 21%. Opal is composed of tiny particles of silica and due to its amorphous state, it is considered a mineraloid instead of a true mineral. The two classes of opal are precious and common, which can be visually differentiated. Precious opal displays “play of color”- a rainbow effect produced by the diffraction of white light by an orderly arrangement of tiny silica particles. Common opal does not display this rainbow effect and is usually solid in color. The arrangement of the silica particles is not ordered, and light is not diffracted symmetrically like that of precious opal. Finding ways to synthesize opal in the laboratory are ongoing, with robust synthesis strategies such as the Stober and Gilson Methods. Both methods utilize tetraethyl orthosilicate (TEOS) to produce uniform sized silica nanoparticles. The particles are typically arranged, dried, and hardened. In this study, an alternative synthesis method utilizing commercially available silica crystals and an electrolyte mix was employed in effort to synthesize opal. Samples will be analyzed using X-ray diffractometry to determine the crystalline phases, if any, in the opal, and compare those findings to opal synthesized using the Stober method.

Geological Society of America Abstracts with Programs. Vol. 51, No. 2

doi: 10.1130/abs/2019SC-327538

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