When opal miners have to work underground in search of seam opal(those mines at Lightning Ridge, Coober Pedy and Andamooka) a miner will stake his (or her) claim, secure the funding needed to purchase the appropriate equipment, and then sink a shaft some 40 feet down. With this shaft as a base, they will then tunnel horizontally outward in search of opal.
Until the 1970s, the miners would tunnel outward using hand tools. Nowadays an auger is used. An auger is a giant drill which can bore a circular tunnel in a matter of hours.
One the tunnels have been made, various equipment is lowered down, depending on how much funds the miner has. Black opal mines typically use quite a bit of expensive equipment, as black opal is the most lucrative opal to mine.
Claims are granted in either 50- or 100-meter lengths. Miners typically have not kept accurate maps of their tunnels, and on occasion heavy earth movers moving topside have actually fallen into tunnels below!
Opal mining, therefore, is a dangerous business, for a variety of reasons.
Anthropologist Louis Leakey discovered the earliest known opal artifacts in a cave in Kenya. They have been dated to about 4000 B.C. The current theory is that they were mined in what is now Ethiopia, and perhaps sold or traded to people who then returned to what is now Kenya.
Wealthy citizens in ancient Rome loved to acquire opal – it wa srarer than pearls and diamonds. The Roman writer Pliny shares tales of opal coveted by Marc Antony for Cleopatra, in 50 BC.
No one issure where this opal acquired by Roman citizens came from. Pliny believed it came from India, however experts believed that it was mines in what is now Hungary that supplied these gems.
In the Middle Ages, Hungary mined opal which it supplied to Europe and the Middle East. The civilizations of Mexico, Peru and Honduras supplied their own gemstone wants from their opal mines.
Conquistadors returning to Spain brought opal with them in the early 16th century.
However, since the late 1800s, it has been Australia that has dominated the opal market. Austtralia produces 90% of the world’s opal. About 20 other countries supply opal as well – Canada, Ethiopia, Guatemala, Indonesia, New Zealand, Peru, Poland, and Zambia. Gem opal typically comes from the USA, Brazil and Mexico.
