This faceted 105-ct contra luz opal represents some of the finest play-of color mate- rial found at Opal Butte, in northeastern Ore- gon, during the 1987-1 988 mining season.

Opal is essentially hardened silica gel, with the chemical formula SiO2・nH2O and a water content of 5 - 20% by weight. Opals form from the deposition of particles in circulating silica …

Everything uploaded into OPAL must be in the form of a scanned PDF document. Please note that Original Transcripts must be uploaded by Department staff and not by the applicant.

What is the OPAL? The Requirements & Guidelines are standardized to provide a structure. The OPAL allows you to demonstrate your practice, with illustrations and concrete evidence from …

Opals display a phenomenon known as play-of-color. When a stone has play-of-color, it is referred to as precious opal. The main categories of precious opal are white, black, boulder, …

An Opal Introduction e of a six-part series on Opal. Here is a complete list of our Opal articles: An Opal Introduction, Common Opal, Black Precious Opal, White Precious Opal

The OPAL is intended for teachers, educational leaders, coaches, and others to conduct focused classroom observations for three potential purposes: research/evaluation, professional …