“The opal formation at Andamooka is different from any other. The opal bearing areas are covered with a sandy clay called kopi (kaolinized sandy clay). Mixed in this area are boulders of quartzite (which miners call river rock). Occasionally when these quartzite boulders are near the opal level they will have lines of opal filling cracks in them. (These are called painted ladies.)

Just above the opal level, the kopi and boulders are sometimes joined by another unusual formation called concrete. The sand has been stuck together by opal. It is hard to cut, but very porous and light. (It is not very valuable as a jewelry stone, but when treated to turn black, it can produce an attractive play of color.)

The opal level is the point where the kopi meets a layer of mud clay. The Mines Department claims that nearly all opal is found within 0.2 meters vertically of this meeting place. This narrows the miner’s search.

The solid opal forms in a round shape that miners call a blob. Technically, it is called a lens. Only occasionally are seams of opal found, as well as matrix opal.”

The opal in this area is mined by the shaft and tunnel system.

Most commercially set opals that you see in jewelry stores were set improperly, during Downiing’s heyday in the 1990s, and I mention his strictures here because you never know when a jeweler might not go back to the bad old ways necause it takes less time, even if the jewelery suffers.

Downing points out that opals are not too fragile to wear, if only they are set properly.

Some jewelers set opals in mounting reserved for faceted stones, like diamonds. And since opals are more fragile than diamond, they do indeed break when set in that manner.

The most fragile part of a cut opal is the bottom edge, so to prevent the gem from cracking in its setting, it should be completely surrounded by, or nestled in, metal. On no account should you purchase opal sitting up in a set of prongs, with no gold or other medal around it.

Natural opal – natural precious opal cut to include common opal or potch in one piece
boulder opal - opal cut to include ironstone, rather than common opal or potch)
Doublet – A natural opal assembled with common opal, potch, or any other material
Triplet - the same.

Some dealers attempt to sell assembled opal and ironstone as boulder opal – don’t be fooled!

A wavy line between the two indicates a natural boulder opal. A straight line = an assembled boulder opal, i.e., a doublet.

Boulder opal is famous for its color intensity. No othr opal type can match the size and vibrancy of the color spots that are visible when the piece is held at angles to catch the play of fire.

In adition, the three-dimensions of boulder opal make it easier for jewelry designers to do some unique things with their jewelry. Matched earrings are particularly popular. “Splits” – a boulder opal split in two so that one half is a mirror image of the other half, are as rare as matched emeralds, rubies or colored diamonds…and their prices reflect this.

Boulder opal is also renowned for its durability. Because water content of boulder opal is low, it almost never cracks or crazes as the years go by.

Lightning Ridge, on the other hand, is significantly cooler, and there’;s enough moisture to support tree growth (albeit, scrub trees).

However, there’s till not a lot of water, so what the miners do is form “wash cooperatives.” Since it’s easier to find opal when its wet, all the dirt and gravel dug out of a mine is driven to one od many dam sites. There, the material is dumped into an agitator. The dirt is tumbled around for 4 to 5 hours, sprayrf with water, so that most of the gravel pours out of the sides of the agitator. The rest of the material slides down into an area where the miners look it over, inspecting each piece by hand.

The residue, the grit and gravel, is dumped into “mullock heaps” near the top of the dam.

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.

Check out the boulder opal on auction today!

	YowahOpals*40.70Cts Opal Pendant – Australian Opal yowahopals	20.00	-	-	1 hour 48 minutes
	YowahOpals*62.85Cts Queensland Opal -DRILLED PENDANT yowahopals	79.99	-	-	1 hour 48 minutes
	YowahOpals*48.55Cts Queensland Opal -DRILLED PENDANT yowahopals	8.99	-	-	1 hour 48 minutes
	YowahOpals*15.60Cts ‘Aussie’ Boulder Opal – Leather Cord - yowahopals	12.50	-	-	1 hour 48 minutes

Loose opals on the surface, called floaters, are rarely found these days. After a hundred years of miners looking for opal, they’ve all been found!

Today, miners search for “slips” vertical opens in the ground that let ground water seep into the earth. They use dousing to find these slips.

Open cast, also known as surface mining, finds opals at a shallow level. Boulder opal miners in Queensland dig for the shallow levels, for example. At Mintabie, miners use bulldozers to dig swathers 100 feet deep.

However, underground mining is the norm at Lightning Ridge, Coober Pedy, and Andamooka, which have seam opal.

Wollaston purchased the bag of black opal – not for a great deal of money – and placed a standing order with Nettleton for more. This was the transaction that put Lightning Ridge on the map, and today, it is perhaps the most important opal field in the world.

In 2000, author Fred Ward described life at Lightning Ridge as “raw…a hideaway for loners, a place for getting lost. Folks go by their first names, keep no records, and guard information. Opal is an all-cash business.”

Nine years later, the situation has not changed much. Opal mining in Australia still has pretty much of a “Wild West” flavor about it.

In the late 1800s and very early 1900s, the only opal; mining in Australia was at White Cliffs, which was a light opal mine. However, around 1900, black opal was discovered in Lightning Ridge, 800 km southwest. (Lightning Ridge an area about 700 km northwest of Sydney, on the northern border of New South Wales.) At the time, it was grazing land.

The actual discoverer was a miner named Charlie Nettleton. The mine at the Cliffs was playing out, so he went walking…and walking….in search of gold rather than opal.

He stopped in Lightning Ridge and camped with the Ryan family. They were opal miners, who had discovered black opal….which was unlike anything else he’d ever seen. He sank an opal shaft in 1902, with no luck. In 1903, he shifted camp closer to where seven other men were digging. Here, in early 1903, he found opal. He sent a parcel of his findings to a gem dealer in Sydney, who rejected it, calling it a “worthless form of matrix.”

To be continued!