Opal can be found around the world, with Australian #opal, specifically #black opal regarded as the most precious and valuable.
Australia
Solid (black, dark, light, crystal)
Boulder
Matrix
Ethiopia
Solid (volcanic, hydrophanic)
Mexico
Solid (fire opal / water opal)
Boulder (fire opal matrix)
Brazil
Solid (sedimentary light opal)
Peru
Solid (blue and pink common opal)