White Cliffs is a small town located 95 km north of Wilcania in New South Wales. Opal was 1st discovered there on 1889 and by 1897 there were thousands of miners in the area. The opal was found in white sandstone country indicating it had once been part of a vast inland sea. Beneath this sandstone , at various depths depending on the terrain, lies a gritty layer of "opal dirt". Below that there is greasy clay which usually does not produce opal. The lst layer of sandstone above the opal layer is often harder and more silicious and the miners called it "the band"
It was late May and the weather in Melbourne was getting colder and wetter. It was time to escape north to a better climate and to do some fossicking and fishing.
Barbara and I packed the caravan and Hilux with all of the essentials for an unplanned trip. Plenty of food, the kayaks, fishing gear, gold detector, gold pan and sieves just in case we ended up in an opal or other gem-field. As if we wouldn't?
The early days at White Cliffs were quite interesting and somewhat different to most other opal fields. The information in this post comes mainly from the book "They struck opal" written by E F Murphy, "The Opal Book" by Frank Leechman and "The Lightning Ridge Book" by Stuart Lloyd.
E F Murphy was born at Mt Edgerton in Victoria in 1862. He went to school at St Patricks College in Melbourne and was well educated. He was a young man of twenty when he came to White Cliffs and was the fifth miner to take out a lease at White Cliffs. This occurred soon after the first finds of opal were made at this location and so had first hand experience of what conditions were like at the field.
Whenever we think of opal we usually think of gems used in jewellery, but there are some opals and other gemstones which portray beautiful and intriguing patterns, but which are not necessarily suitable for use as jewellery.
Some of the stones shown below are from my collection and while not the most valuable, they are still amazing for the patterns and colours they exhibit.
Lightning Ridge is famous for its "black opal" but it also has its share of strange buildings. The strangest of all has to be the "Universe Observatory" or "Astronomer's Castle" built by Polish Alex Szperlak.
There are many amazing sights around Lightning Ridge, but few better than Amigo's Castle.
Vittorio Stefanato, known locally as "Amigo", opal miner and castle builder, started his project in 1985 when he started getting tired of opal mining. Initially he sourced his stone from his mining lease but soon had to travel to all areas around Lightning Ridge as his castle grew in size.
Opal at Andamooka is found in a narrow band of depths varying up to 600 mm. In this bed there are many boulders of strongly bonded quartzite of varying sizes.,Today, as you wander among the great piles of disturbed overburden which is mixed with the old opal level , you will come across many of these boulders. They are extremely hard and difficult to break.
The opal fields of Australia were formed at the bottom of a large inland sea. In this sea there were all sorts of marine creatures including turtles, crocodiles, dinosaurs, all sorts of fish and of course shellfish. As these creatures died their bodies sank to the bottom of the sea and were covered with sand and silt. Over millions of years the sea dried up and various clays and sand were deposited over the sea bed. The bodies of the sea creatures obviously rotted away and the bones and shells, being made of calcium carbonate, were dissolved by acids in the soils. This would have left cavities in the shape of the dissolved creatures. Silica then seeped through fissures and cracks and filled these cavities which acted as casts for the silica that filled them. In some cases the silica turned into opal and the reult was opal in the exact shape of the shell or bone that had been deposited on the sea bed so long ago.
It was all very good finding opal in the early days but if no-one wanted to buy it, then there was little use risking your life trying to find it. Still this did not deter the brave souls who ventured into the harsh environment of central Australia to chase opal. In the 1880's opal had been found in Queensland and miners had established themselves in various areas where opal had been found. At that time they realised they had found a valuable and rare gem but there was no-one to buy it. Miners would hoard the best quality opal and throw away the more inferior material. There are records of miners with sugar bags full of top quality opal but it was of no use to them in outback Queensland.
Yowah is a small town in south west Queensland and is famous for the Yowah Nut which is only found here and nowhere else. The yowah nut is a relatively small, hollow ironstone concretion in the shape of a nut. They occur in closely packed horizontal layers with sandstone overlaying these beds of nuts. In some cases the centre can be filled with gem quality opal but in most cases they are filled with air, powder or some other non valuable material. Yowah also has some really beautiful matrix opal which is the same ironstone concretion often with small flecks of precious opal interspersed through the ironstone.See my post on Yowah Nuts post for more details.