Growing Opals—Australian Style

by Dr. Andrew Snelling on December 1, 1989

In a dusty old wooden shed on a side street in Lightning Ridge, New South Wales, Australia, a bush scientist trying to discover the origin of opal has been able to ‘grow’ opal which is virtually indistinguishable from the mined precious stone.

Len Cram’s shed has to be one of the oddest, out-of-the-way research laboratories anywhere in the world. On the walls are shelves with row upon row of bottles, peanut butter jars, and other containers. Each is covered with a plastic lid and rubber band with data scrawled over it.

The jars and bottles are filled with a milky-coloured liquid, and at the bottom of each lies a few centimetres of residue. On closer examination, it has the unmistakable colour and flash of the most beautiful precious opal one could imagine. Yes, man-made opal, grown in the laboratory, over a short period of time—not millions of years!

Len’s opals have fooled old miners who have lived in Lightning Ridge all their lives. So skilled has Len become that he can have them believing his opals are from any one of the various opal fields around the town.

Far from boasting about his extraordinary discoveries, Len is usually reluctant to talk about them. In a town where people’s livelihoods depend on the real stuff coming from the ground, there is much suspicion about his work. But Len’s main object is not to manufacture opal. Rather, his is purely a quest to find how opal forms.

Other theories upset

Len Cram is a committed Christian with a dogged determination in his work. His experiments have turned traditional theories about opal upside-down, even challenging accepted ideas of evolutionary geology and its alleged millions of years for the formation and age of opals. But Len is not a sophisticated scientist—just ‘10 per cent inspiration and 90 per cent perspiration’!

Few people know more about opal than Len does. Even scientists who refuse to acknowledge his work admit he is a world authority on the subject.

Len left school when he was 15. Self-taught, with a very analytical and inquiring mind, his formal training came only after he had completed most of his opal-growing research. This includes an earned Ph.D. (for a thesis on his opal research)—academic credentials he says he needed so that his work would be accepted in scientific circles!

Len started his association with opal in Queensland in the 1950s. Even then, he wondered if he could grow opal, and so began his first experiments, using of all things honey and sulphuric acid. Eventually, in 1962, he moved to Lightning Ridge, in New South Wales, where he began in earnest to pursue his dream of making opal.

Thus began an ongoing scientific adventure. He studied every scientific paper on silica he could lay his hands on. He went through years of experiments—trial after trial, failure after failure. Each experiment was carefully recorded. Results were documented. Often discouraged, but still hopeful, he carried on.

CSIRO research

At the same time Len was doing his work in the bush, others—including Australia’s CSIRO (Commonwealth Scientific and Industrial Research Organisation)—were also doing research on opal. A research team headed by Dr John Sanders of CSIRO’s Material Science Division in Melbourne made some major breakthroughs in explaining the colour and construction of opal.1

Using an electron microscope, Dr Sanders found that opal was made up of millions of tiny silica balls in a regularly arranged pattern. In between each of these balls were found even smaller holes or interstices, through which light is diffracted, that is, when white light or ordinary sunlight shines through the holes, it is split into colours. In opal where the balls were small, the colours produced were the darker colours of the rainbow—violet, indigo and blue. When the balls were large, yellow, orange and red colours were produced. Precious opal is found when the balls are in a regularly arranged pattern. In potch or common opal there is no set pattern.

Dr Sanders and his team produced an artificial material in 1968 that was comparable to natural opal. They took out patents in England and the United States. However, like Len Cram, they realized the potential dangers of their work (e.g. if opal could be cheaply produced artificially it would completely undermine the value of natural opal and thus bring economic ruin to the opal mining industry). They thus tried to keep a lid on their breakthrough.

Meanwhile, Len was eventually able to use the CSIRO research for his own work. He did more and more experiments, all of which failed to produce results—‘successful failures’. On the wall of his laboratory he has pinned two sayings around which his work is based: ‘In this laboratory, success is never guaranteed and failure is never permanent’, and ‘Fear of the Lord is the beginning of all wisdom.’

Success at last

It was not until 1975 that Len had his first success. He poured a bit of ‘this’ and a bit of ‘that’ into a bottle. He gave it a shake, put it on the shelf, and forgot about it. Sometime later he and a friend were in the shed-laboratory doing something else when his friend noticed the bottle. On the bottom was a three millimetre (one-eighth inch) growth of precious opal!

Len built on this success. Having now unlocked the door, he could grow the most natural-looking opal anyone could imagine. On his shelves are Andamooka blue/greens; Coober Pedy whites and ‘crystals’; Mexican oranges, and Lightning Ridge blacks—all grown in his shed. The opal is so natural-looking that there are different colour bars with different patterns, and lines of potch between them. Len’s opal looks real, simply because it is real. His process apparently is a mimicking of the process which formed opal in nature. And Len’s opal grows at normal room temperature without any pressure or mechanical assistance. Furthermore, Len’s latest opal looks identical to natural opal even under the electron microscope. Other attempts at manufacturing opal, including those of CSIRO, look noticeably different.

Len’s work is motivated by his strong Christian convictions. He is a creationist and claims his experiments discredit uniformitarian geology theories of slow-and-gradual opal formation (evolution) over thousands and millions of years. While developing his system for growing opals, he learned a great deal about how opal is formed. Len believes it took only a few months within suitable portions of the voluminous sediment layers laid down catastrophically by the Great Flood—and he says he can prove it.

Evolutionary theory wrong

Current scientific theory, based on the geologists’ uniformitarian belief in slow and gradual processes over millions of years, states that opal formation was a sedimentary process.2 Silica gel (a warm water solution supersaturated with silica) was deposited over millions of years, layer after layer, filling in cracks and spaces in a parent rock, which is often a friable sandstone, locally (i.e. in the opal mines) called opal dirt. Over millions of years more the gel supposedly slowly dried out to become hard. It has been suggested that it took around five million years for about a centimetre (a little more than a third of an inch) of opal to develop, perhaps through rain washing the silica gel into the opal dirt.

But Len has proved that the opal formation process is probably very different to this. In his jars, the first touch of colour appears within 15 minutes! In three months he gets more than one centimetre (half an inch) of vertical growth. Len says the longest part is the drying-out process, as the water contained within the developing opal structure is expelled over subsequent months and years. The actual formation of the opal takes only a very short time (only a matter of weeks). The accepted evolutionary theory, however, says that the water evaporated and the opal formed as the silica gel dried out. This is untrue according to Len. Natural opal, he says, was not formed by flows of silica gel, but went hard (indurated) under water.

Len says that he has succeeded because he was prepared to look at the scientific problem completely unshackled by evolutionary and uniformitarian assumptions—an attitude different from that of other scientists.

Although some of the scientific theories of CSIRO’s Dr Sanders are in conflict with Len Cram’s, Dr Sanders has described Len’s work as remarkable. ‘He has shown incredible dedication in trying to find how and why opal was formed. The Japanese have made opal but it is nowhere near the same as those produced by Len’, Dr Sanders says.3 No one else has managed to capture the fire of the precious opal, or the natural look that Len’s opal has.

The recipe

There is no doubt that Len has demonstrated that opal can form quite quickly. All it takes is an electrolyte (a chemical solution that is electrically charged), a source of silica and water, and some alumina and feldspar. The basic ingredient in this recipe for making opal is a chemical called tetraethylorthosilicate, or TEOS for short, which is an organic molecule containing silica. The amount of alumina which turns to aluminium oxide determines the hardness of the opal.

The opal-forming process is one of ion exchange, a chemical process that involves building the opal structure ion by ion (an ion is an electrically charged atom, or group of atoms (molecule)). A reasonable analogy would be that of the growth of a crystal within a chemical solution. When the proper chemical mix is present, a tiny crystal forms in the liquid. Then the crystal grows larger and larger until the chemicals needed to make it are used up from the solution. Opal is not a crystal, but Len has shown that it grows in much the same way. The ion exchange process starts at some point and spreads until all the critical ingredients, in this case the electrolyte, are used up. This initial formation process takes place quickly, in a matter of months, in Len’s laboratory.

After the initial formation in a matter of weeks, the opal has beautiful colour patterns, but it still has a lot of water in it. Slowly over months, further chemical changes take place which consolidate the silica gel. These changes create varying patterns of colour and ‘squeeze’ the water out. It is not the initial forming that takes time; rather, it is this restructuring. Only after the opal has restructured is it stable and useful as a gemstone.

Rapid formation in nature

So now we have a new explanation of how opal is probably formed in nature. At some point in the host rock, the correct mixture of electrolyte and other ingredients is present. The chemical process starts and expands outward. It transforms the host sandstone or opal dirt into precious opal through the ion exchange process. As it does, it uses up the electrolyte. When it is all used up, the process stops and no more precious opal forms. After this initial formation, the silica gel naturally restructures, becoming more compact, ‘squeezing’ out water as it does.

This simple experimentally verified process can explain how opal formed in so many different ways. The so-called nobbies (round nodules of opal) of Lightning Ridge (and probably the ‘crystal blobs’ in Andamooka) are thus the result of a small pool of electrolyte in which the opal formation process started. As the opal grew from the centre out, a concretion or roundish shape was created. The size of the nobby or nodule was probably determined by how much electrolyte was available.

One wonders how a nobby, or a spot of opal in Mexican rhyolite (a volcanic lava rock), could have been formed under the sedimentation processes of standard evolutionary/uniformitarian theory. Where did the gel come from? How did it travel into the space it supposedly filled? There are usually no cracks to provide access. Len Cram’s explanation solves this problem. With the necessary ingredients already part of the lava rock, the process started from the inside out, transforming the matrix into precious opal as it proceeded

Seams (or layers) of opal also can be explained in this way. The electrolyte initiates the ion exchange and the process takes the path of least resistance, that is, along the layering in the host rock.

Transformed into opal

Len has a bottle where he has put opal dirt from Lightning Ridge in the bottom and his solution on top. The layer of opal formed on top of the opal dirt, but then, strangely, a pocket of precious opal began to grow in the dirt. The opal dirt (or sandy grit) was literally being chemically transformed into precious opal. In another of his bottles, precious opal has grown in horizontal layers or seams in the opal dirt, one above the other. Each seam has varying qualities, colour bases and patterns. Thus seam opal is not necessarily a sedimentary deposit in previously existing cracks in the opal dirt. Rather the chemical reaction which creates the opal has made the seam where no crack or seam previously existed.

There are other problems with the so-called sedimentation theory which make Len’s experimental explanation far more believable. In some opal fields there are often several large seams of opal deposits, sometimes six or nine metres (about 20 or 30 feet) across, lying one on top of the other with little space between them. If these opal seams had originally been open cracks in the host clay, how could this soft clay have stayed suspended for millions of years with large long cracks within it without collapsing while waiting to be filled with opal? No wonder geologists have difficulty in explaining opal formation in such occurrences!

There is also a lot of natural opal that is impregnated with ‘opal dirt’ which has a lower specific gravity than does silica in solution. This opal dirt should thus have floated to the top of the gel if the sedimentation theory were correct, rather than being caught up in the middle of the opal as is so often the case.

Both these observable details completely discount the evolutionary theory of silica gel sedimentation over millions of years.

Potential confirmation of the comparability of Len Cram’s experiments with natural opal formation comes from an experienced Northern Territory opal miner. He recently recounted how after discovering some high grade colourful opal underground, he was dismayed to find that after only short exposure to sunlight, the opal lost its colourful patterns.4 This suggests that some mined opal is not yet stabilized, pointing to recent formation.

This fascinating scientific story is not yet complete. The usual explanation for differences in base colour in opals is the presence of impurities. Len’s research has shown that this is not how the base colour is formed. He has shown that the chemical composition of black opal is identical to that of white or other types. Rather, it is the structure of the opal which creates the base colour.

Vital creationist research

This again is a revolutionary idea, but as before Len has the proof in the bottles in his laboratory. He has opal growing where he initially mixed various dyes to make the solutions black. Sure enough, there sits a black liquid on top of a growing layer of pure clear opal. But in another jar the liquid is clear and the opal is black. Len maintains that every black opal in Lightning Ridge (and 98 per cent of the world’s black opal comes from Lightning Ridge) was originally white—he has seen white opals turn black in his bottles. So much for the old theory that the colours are produced by impurities!

All this sounds exciting but, as always, there is a catch. Len has proved that good stable natural opal hardens while still underwater, because his opal is slowly doing the same. But he hasn’t so far waited the few years or decade necessary for completion of the process to be able to pour the water off his opal and cut it. Instead, he has siphoned the water off through a small hole in the plastic top over his jar and allowed the opal to slowly dry out over a number of months. And here is the ‘catch’. The forced drying caused the opal to crack. Len is working on this problem but has not solved it yet.

Len’s opal is not yet ready to replace natural opal. He doesn’t intend it to. However, what Len’s experiments have done is provide a whole new explanation of how opal is formed, in only a matter of years. His short time-frame explanation, consistent with the biblical framework, can readily account for the field observations of natural opal in its host rocks. Furthermore, the most likely explanation of the opalization of fossil bones is now therefore the same replacement (ion exchange) process that Len has demonstrated in his laboratory. The evolutionary ‘textbook’ story of opal formation slowly over millions of years is going to have to be rewritten.

Research based on creationist presuppositions is thus not only true and proper research, but continues to contribute to true scientific endeavour.

However, there are also practical applications. Len Cram’s creationist research into rapid opal formation has now provided a new model and exploration target in the search for more opal in existing opal fields and, more importantly, for the discovery of new opal fields.

If most of the host sediments were catastrophically deposited recently in Noah’s Flood and opal formed rapidly, why should the uniformitarian geological time-scale, with its millions of years, limit exploration targets for new opal deposits to so-called Cretaceous sandstones? All sandstone strata that resemble the host rocks of known opal fields such as Coober Pedy (South Australia) and Lightning Ridge (New South Wales)—‘Cretaceous’—or Mintabie, South Australia (‘Ordovician’) should be regarded as prospective, regardless of their inferred uniformitarian geological age.

Related Magazine Articles

Creating Opals
Creation 17:1 (December 1994)


  1. Sanders, J.V., Colour of precious opal, Nature 204(4964):1151–1153, 1964.
    Sanders, J.V., Diffraction of light by opals, Acta Crystallographica A24(4):427–434, 1968.
    Murray, M.J. and Sanders, J.V., Close-packed structures of spheres of two different sizes II. The packing densities of likely arrangements, Philosophical Magazine A42(6):721–740, 1980.
    Sanders, J.V., Jelly opal from White Cliffs, The Australian Gemmologist 14(7):161–165, 1981.
  2. Darragh, PJ. and Gasking, A.J., The nature and origin of opal, The Australian Gemmologist, no. 66, pp. 5–9, 1966.
  3. As quoted by Gerard McManus in ‘The man who grows opals’, Australasian Post, 6 February 1988, pp. 18–20.
  4. D. McLaughlin, personal communication, July 1989.
Originally published in Creation 12(1):10-15, December 1989

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Answers in Genesis is an apologetics ministry, dedicated to helping Christians defend their faith and proclaim the gospel of Jesus Christ effectively. We focus on providing answers to questions about the Bible—particularly the book of Genesis—regarding key issues such as creation, evolution, science, and the age of the earth.