Opal Formation Theory
Opal occurs worldwide in all types of rock but sedimentary rock possesses the most favourable environment for stable opal formation. For opal to form we need two major hydrous events at the same time. These events occur rarely together. The first of these is a body of water forming a brackish slightly acidic sea covering (preferably ) sedimentary rock. Secondly we need an injection into the sediments of an alkaline solution under moderate pressure and low heat (in Australia this is provided we believe by the waters of the Great Artesian Basin). The second solution dissolves silica in the sandstone formations and carries it in solution until it comes in contact with ground water which has soaked through the sandstone to a point of saturation. This usually occurs at different depths of up to 200 feet or more in places following existing water tables.
Such conditions would have occurred in a global event such as the “Noachian Deluge” (contrary to popular science). Such an historic event is recorded in the account of “Noah’s flood” in Genesis Chapter 6 in the Bible. Evidence of such an event is constantly encountered when mining for opal. Many feet (greater than 6 meters, sometimes over 20 meters) of sandstone strata of uniform particle size and colour are encountered during mining. We also encounter millions of cavities left from fragments of broken wood and other plant material. Some of these are filled with potch or opal. This form of opal it called Pipe Opal. These also occur over the entire area of the Australian opal fields. Sediments thousands of meters in depth have been drilled and logged by oil companies in Western Queensland and Central Australia. I have a small opal with what appears to be a flower petal (under 40x magnification) partially folded and trapped within the opal. This would suggest a sudden event rather that something that happened over an extended period of time. Also we have found bubbles of water trapped within opal with a bubble of air.
When the two waters meet, the silica precipitates out as sub-microscopic spheres. When these spheres are uniform size and arrayed in a regular and tightly stacked pattern, precious opal is formed.
Once these geological events subside, the opal now as a gel, solidifies. When the land mass (now called Australia) was buckled upwards and raised above sea level this gel began to solidify under pressure.
Where does the opal form? Opal is generally found in conjunction with faulting and dipping of the country rock (sediments). Water soaks naturally downwards until it reaches an impervious layer or is interrupted by slides and faulting and/or changes direction, these little geological hiccups are where the opal precipitates out. I have found relatively flat boulders dipping at 10 degrees, some with a slight bend in the middle causing slight compression of the boulder. Generally it is thought that opal forms the lowest part of a boulder but in this instance it was not the case. Instead the opal occurred above a slight bend in the boulder and no opal in the bottom of the boulder where it as normally found.
Again a level of boulders about 5cm thick was dipping at 15 degrees at the top end of the run (highest point), one boulder dipped in the opposite direction and carried some good gem opal, all the rest of the boulders in that patch were empty.
No matter when the opal was formed or how, this is only a brief summery based upon my own personal observations. There are many more events and discoveries I have personally made during more than 25 years involved with prospecting for new deposits and mining for boulder opal.
Nothing is more confronting than finding a magnificent perfect rough gem. These are extremely rare and beautiful. If all things happened by chance over millions of years (as we are taught), how come all things beautiful are rare and even in an apparently abstract formation such as sedimentary deposits there is order and design?
When gazing into a brilliant natural rough gem it only reflects the brilliance of design by my creator, God himself! All glory to God for this magnificent gem that that He has seen fit to allow me to derive an income from.
There is however a greater gem that I have found. That is the salvation my wife and I have received and enjoy through simple and personal faith in the greatest most brilliant act of God in sending His only son to shed his blood and suffer the punishment for the sins of every man, woman, boy and girl on the cross of Calvary, regardless of race or creed.
God gave warning through Noah’s flood. He will again judge the world and warns of this through his word the Bible. If mankind continues to ignore His warnings all men will suffer in the final judgement . We need to individually acknowledge our sinnership confessing one’s sins before God and accepting the Lord Jesus Christ as your own and personal saviour. (That’s faith plus nothing else, not good works, not money, not anything!)
Acts ch 16 v 31 “Believe on the Lord Jesus Christ and thou shalt be saved”.
READ YOUR BIBLE! If you don’t have one we can send one free of charge, no strings attached, no obligation. the only thing we ask is that you read it!
Hope you have found this interesting and helpful.
Remember when all seems lost, God is still intensely interested in you and loves you enough that he gave his Son to die on your behalf. 1 Timothy ch2 v 5 “There is one God and one mediator between God and men the man Christ Jesus”.
Kind regards to all from Opal Endeavours.