This article is from
Creation 44(4):12–15, October 2022

Browse our latest digital issue Subscribe

Fiery opals from the Flood

These stunning gemstones formed at a unique time in Earth’s history.

© Daniel Nagy | Dreamstime.comround_opal


What do Cleopatra, Napoleon, and Queen Victoria have in common? They all owned opals and loved them.

Opal (fig. 1) is an amazing and spectacular precious stone that has been sought after for thousands of years. In the Middle Ages opals were mined in Hungary, but in the late 1800s Australia began supplying the gem from many different opal fields. By some estimates, over 90% of the world’s opals now come from Australia (see Where are opals found? below).

When I visited the opal field at Coober Pedy in South Australia, shops had all sorts of opal jewellery on display. One sign said, “Many millions of years ago when dinosaurs roamed the earth the processes of creation forged a unique gem which somehow appeared to entrap fire and light and the opal was born.” It seems dinosaurs and millions of years make the opal more desirable in people’s minds.

For a long time, the prevalent thinking was that normal weathering formed opal. That is, rainfall, groundwater, and chemistry over hundreds of thousands of years. However, research has demonstrated that opals form much, much faster. There are multiple lines of evidence not only that they formed quickly, but also that they formed during Noah’s Flood.

Opal miner demonstrated opal forming quickly

Amazing evidence that opal forms quickly was demonstrated by Dr Lenin George ‘Len’ Cram, an opal miner and researcher who moved to the Lightning Ridge opal field in the early 1960s.1 Len has written popular books about opals2 and is famous for his research into how they form. A Christian, he was frustrated by geologists who denied the biblical Flood, and who claimed opal took millions of years to form. Dr Cram was convinced they formed within the biblical timeframe.

© Oksana Tabachenkova | Dreamstime.comfig1_opal_blaze
Fig. 1. The iridescent rainbow colours of opal blaze like fire, changing and flashing as the prized gem is turned.

In a crude tin shed on his property, Len started experimenting with different sediments and solutions. In the mid-1970s, after years of failure, he was able to form opal in jam jars in months. In fact, he was able to form different types of opals, such as blue, green and orange. And also the valuable ‘black’ opal, in which the colours occur within a dark potch background.

They looked real and natural, even under an electron microscope. He conclusively demonstrated that opals form rapidly.

Len put some of the Lightning Ridge sediment—silica (quartz) sand with the formula SiO2—into a jar. Quartz is very hard3—it cannot be marked with a steel knife. Len then poured a solution into the jar which included an organic substance containing silicon (tetraethyl orthosilicate, aka tetraethoxysilane (TEOS) or tetraethyl orthosilicate is Si(OC2H5)4). The combination of reagents in the solution enabled the silica sand to absorb water and become hydrated. Tetraethyl orthosilicate reacts with water to deposit silica while forming ethanol, the alcohol in alcoholic beverages. Within a couple of weeks, the opal colouring appeared in the sand.

Atom by atom, the silica sand was changed chemically into precious opal, by a process of ion exchange. The process began at a point in the sediment and spread until all the relevant constituents of the solution were used up. That means that ‘seam’ opal was not necessarily deposited in pre-existing cracks in the host sediment, but formed from the sediment where no seam previously existed.

The first signs of colour can appear in as little as 15 minutes. For a few months the opal continues to grow, forming a band, or seam, that can exceed a centimetre in thickness. For months or even years the opal is still soft and gel-like. However, with time, even while under water, the opal gel gradually expels its excess water and sets hard.

Len’s experiments have proved that opal does not need long time periods to form. They also give insight into how opal could have formed in nature. As the host sediments were deposited, the associated water acquired solutes giving it chemical properties that transformed silica into opal. Opal formation continued until the active chemicals were used up. Then with time, the opal gel restructured and hardened.

Bacteria prove opal formed quickly

Another amazing evidence that opals not only could but did form quickly was revealed in 1999 by Professor Hans (Ted) Behr at the first Lightning Ridge Opal Symposium.4 He announced that he had found large numbers of fossil microbe communities in potch opal.

The preserved presence of these bacteria means the opal must have formed fairly quickly, otherwise the organic structures would break down. In fact, it was concluded that the time needed ranged from just weeks to months. Later, research by Dr Karen Behr identified the most common bacterial types as the aerobic (oxygen-requiring) myxobacteria and actinomycetes (fig. 4).

© State of New South Walesfig4_filaments_of_micromonospora
Fig. 4. Filaments of Micromonospora bacteria that grew within the pore spaces between silica spheres of potch before final hardening. Watkins et al, ref. 4.

The research revealed that the opal containing these must have formed at a time when the sediments were reasonably fresh and still oxygenated and unconsolidated, not thousands of years after they were deposited.

The microbes provide other clues about the sorts of conditions present when the opal formed. In addition to the environment being aerobic, it was nutrient-rich, with temperatures less than 35°C (95°F), and near-neutral pH. A nutrient-rich environment would explain the presence of organic compounds that hydrated the silica and transformed it into opal. Also, a nutrient-rich environment is to be expected during Noah’s Flood, especially as the waters were reaching their peak, some five months after the Flood started.5 By that time, they contained vast quantities of destroyed and decaying organic matter, including uprooted vegetation. And the water temperature was slightly elevated due to volcanic activity.6

Clay lenses and flowing water

Opal is found in fine-grained laminated clay lenses (thick in the middle, thin at the edges) within the uppermost sandstone deposits of the Great Artesian Basin. These clay lenses are separated from each other, and range in thickness from several centimetres to several metres. At Lightning Ridge, they are called the Finch Clay Facies.7 The locals refer to the opal-producing zones as the ‘opal level’ or the ‘opal horizon’.

When geologists encounter clay deposits they routinely say the clay was deposited in still water over a long period (to give time for the clay particles to sink to the bottom). However, experimental work has shown that clay does not settle particle by particle but clumps together as floccules, which deposit from flowing water.8 So the Finch Clay Facies was deposited from flowing water, consistent with the Flood environment.

Opalized fossils of all sorts of animals

The clay lenses also contain lots of fossils, and these are also opalized.5,9 Interestingly, the fossils include aquatic animals such as fish and mollusks, amphibious animals such as turtles and crocodiles, land animals such as dinosaurs and mammals, and flying animals such as pterosaurs and birds. These obviously live in a wide variety of habitats, which suggests unusual conditions were responsible for overwhelming and burying them.

The best that mainstream geologists have been able to come up with is to say the sediments were deposited in a freshwater lagoon near the coast. However, such an environment does not seem adequate to fossilize such a range of animals or to explain their excellent preservation. Some of the fossils are found as isolated pieces, but others are concentrated in fossil beds. These beds point to abundant water, abundant sediment, and catastrophic transport and depositional processes.

Plant fossils are also present, and these do not have root systems, indicating they did not grow in place but were transported by water. Plus, it is common to find detritus from plants that were crushed and pulverized, another indication that energetic water transport processes were involved. All of this is to be expected during Noah’s Flood.

Rapid sedimentation and sediment over-pressure

© State of New South Wales | CC BY 4.0fig5_bulbous_diapir_of_opal
Fig. 5. Bulbous diapir of precious opal squeezed from a volume of potch into an area of black opal. From Watkins et al., ref. 4.

Also found in the clay deposits are pipe-like ‘chimneys’ of broken rock called breccia pipes. These vertical (or almost vertical) structures in the clay are shaped as cylinders, cones, and wedges. They range from a few centimetres to several metres across and tens of metres long.

The locals call these pipes ‘blows’, which graphically describes what was going on. In the area, sediment continued to build up rapidly above the impervious Finch Clay Facies. Geologists estimate that more than 1,000 metres (3,300 ft) of sediment were deposited on top of the clay horizons. This increased the pore pressure within the clay, and occasionally the pressurized water was suddenly released through these ‘blows’. The over-pressure also squeezed soft, plastic material into bulbous shapes like teardrops, mushrooms, and domes, a geological formation called a diapir (fig. 5).

All this took place as the waters of Noah’s Flood were rising, not long before they reached their peak.10 This sediment would not have taken long to build up—probably just days, which accounts for the pressure build-up that caused the ‘blows’.

Naturally, after the floodwaters peaked and receded, the overlying sediments were eroded away, leaving the landscape in its present shape.

© Ruslan Minakryn | Dreamstime.comfig6_fiery_opal
Fig. 6. Colourful fiery opal.


Whenever we look at a precious opal with its colourful fiery flashes (fig. 6), we can remember it was created at a unique time in Earth history. The global Flood of Noah’s day provided the special conditions needed. We can marvel at the amazing experiments which have shown that the time needed fits easily into the timespan the Bible records. And when we see the multitude of colours in the gem, we can remember the rainbow that appeared after the Flood, that God gave as His solemn promise never to flood the earth like that again.

Fig. 2. Packing arrangement of silica spheres in precious opal (A) and ‘potch’ opal (B). When white light is diffracted due to the orderly packing of silica spheres, the resultant colour depends on the sizes of the spheres (C).

Opal structure

There are two basic types of opal—precious opal and potch opal. Precious opal with its flashing multiple colours is composed of tiny silica (SiO2) balls all the same size and arranged in a regular pattern (fig. 2A).* The silica in opal is amorphous or non-crystalline, unlike the crystalline form of silica, quartz. This arrangement diffracts white light into the colours of the rainbow. The colour depends on the angle of the light and the size of the spheres, which can vary from 140–300 nm (one nanometre is one billionth of a metre). They are slightly smaller than the wavelengths of visible light (about 400–700 nm). ‘Potch’ opal is lifeless in appearance, and not valuable. It lacks the dynamic colours of precious opal. That’s because either its silica spheres are a mixture of sizes and jumbled erratically (fig. 2B), or the spheres are too small to produce colour. When the silica balls are large, the colours are from the red side of the rainbow: red, orange, and yellow. Small balls produce colours from the other side: blue, indigo, and violet. Green is in the middle. Blue and green are the most common colours in opal, which is generally regarded as more valuable if it includes colours from the red side.
* See Watkins, et al., ref. 4 in main text.
Image Credits: Artistic changes after original figure in ref. 7 (A) inset: © Daniel Nagy | Dreamstime.com (B) inset: CC BY-SA 4.0 International | © Stannatsw | Wikipedia Artistic changes after original figure in ref. 7 (A) inset: © Daniel Nagy | Dreamstime.com (B) inset: CC BY-SA 4.0 International | © Stannatsw | Wikipedia


Where are opals found?

The main Australian opal fields are at Coober Pedy (A), Andamooka (B), and Mintabie (C) in South Australia; and Lightning Ridge (D) in New South Wales (fig. 3). These and other fields are within the uppermost Cretaceous sediments of the Great Artesian Basin. These sediments were deposited during Noah’s Flood as the waters were rising, just before they reached their peak.

Fig. 3. The Great Artesian Basin (shaded blue) showing major opal fields (red). After Watkins et al., ref. 4.
Image Credit: CC BY-SA 3.0 | After (opal field indicators added) | © Tentotwo | Wikipedia
Posted on homepage: 9 October 2023

References and notes

  1. 1.Snelling, A.A., Growing opals—Australian style, Creation 12(1):10–15, 1989. Return to text.
  2. Available from opalshop.com.au. Return to text.
  3. At 7 on the Mohs hardness scale of 1–10, it is outranked by topaz at 8, sapphire 9, diamond 10. Ordinary steel is 4–4.5, although heat treatment can form ‘hardened steel’ with hardness 8. Return to text.
  4. Watkins, J.J., Behr, H.J., and Behr, K., Fossil microbes in opal from Lightning Ridge—implications for the formation of opal, Geological Survey of New South Wales, Quarterly Notes 136, June 2011. Return to text.
  5. Other gems would have also been formed very quickly under Flood conditions, e.g. when water-rich magma cools quickly. See O’Brien, J., Fast, fine gemstones, Creation 43(4):54–55, 2021. Return to text.
  6. These conditions led to the enormous population explosions (‘blooms’) of algae that caused e.g. England’s White Cliffs of Dover; Cox, G., Chalk challenges deep-time dogma, Creation 43(1):36–39, 2021. Return to text.
  7. Pecover, S.R., Australian opal—how did it form, Case Study 1.006, Teacher Earth Science Education Program, tesep.org.au, accessed 12 Feb 2022. Return to text.
  8. Schieber, J., Southard, J., and Thaisen, K., Accretion of mudstone beds from migrating floccule ripples, Science 318(5857):1760–1763, 2007; also creation.com/mud-experiments. Return to text.
  9. Hartnett, J., Opalized fossils and pseudo-fossils, Creation 39(4):52–53, 2017. Return to text.
  10. See Walker, T., The geology transformation tool: A new way of looking at your world, Creation 43(2):18–21. As can be seen, layers assigned to upper Cretaceous are near the peak of the Floodwaters rising. Return to text.

Helpful Resources

Biblical Geology 101
by Michael J Oard, Robert Carter
US $20.00
Soft cover
The Deep Time Deception
by Michael Oard
US $15.00
Soft cover
How Noah's Flood Shaped Our Earth
by Michael J Oard, John K Reed
US $17.00
Soft cover
Thousands ... Not Billions
by Dr Don DeYoung
US $14.00
Soft cover