Opal

Site Listings:

• Publications on Opal Mining - As searched from the InfoMine publications database
• An Overview of Production of Specific U.S. Gemstones: Opal - (USGS)
• Mexican Opal Safari - (Canadian Institute of Gemmology) Report of a visit to an opal mine in Querétaro, Mexico
• Opal Mining Glossary - (Lightning Ridge Australia)