Tips for stone care

How can you tell if a rock has a fossil?

Modern interest in paleontological rarities has given rise to a huge wave of fake fossils, although the fake of paleontological finds has been known since the mid-19th century, when the scientific community of those times began to study fossils seriously. But then all the fakes were of a non-commercial nature, they were more likely incorrectly collected bones or misinterpreted fossils, which ultimately turned out to be monsters worthy of hell. But we will now turn our attention to modern fakes that have flooded the stone markets of the world, and we will also consider the difference between fake and restoration.

And again the Chinese

In 1999, National Geographic held a press conference to unveil a fossilized feathered dinosaur purchased from China that was billed as nothing less than the missing link in the transition from dinosaurs to birds. The dinosaur was allegedly found in Liaoning Province and was accordingly named Archaeoraptor liaoningensis. But soon a scandal erupted in the scientific community – it turned out that this miracle was assembled from a microraptor, a fossilized bird and someone else. The Chinese confidently hold the palm in fake fossils, their 80 percent painted Keyhosaurs filled all paleo-exhibitions, often a fake can only be distinguished with very high magnification, there are even some that cannot be clearly identified even with magnification.

Counterfeits on the trilobite market

Because We primarily specialize in trilobites, let’s talk about them. Over the past three decades, a trilobite mine industry has developed in the Moroccan desert near Alnif, Erfoud and Tabourikt as a result of sensational discoveries of large and bizarre trilobites. Over the years, the industry has developed to become a vital part of the economy, especially in areas of extreme poverty in the high Atlas Mountains where many Moroccan trilobites are found. But finding a rare trilobite is not an easy task, and as a result, a network of workshops producing fake trilobites is developing in Morocco. Today, the fake trilobite industry has reached such proportions that, according to some estimates, the number of fake trilobites has outnumbered the real ones. Due to the simple color of Moroccan trilobites, anyone can choose a paint and it is almost impossible to distinguish them from natural ones, unless, of course, you scratch them or study them with magnification, which is difficult to do when purchasing at opening days.

Fake trilobites on the Russian market and how to distinguish them?

Fortunately, in Russia the situation is much better. Due to the complexity of color and the translucency of chitin, our trilobites cannot be sculpted from polyester resins and other materials so that they are indistinguishable from natural ones, so you will not find cast fakes among the trilobites found in the St. Petersburg area. But, due to the fact that most of our trilobite shells are molting, very often the trilobites are missing some part, because the molting shells often fell off the trilobite in parts. Therefore, sometimes during preparation it is necessary to substitute a donor part from another sample in place of the missing part. The value of such a trilobite, as a rule, decreases very little, if at all. During a search, when a trilobite is removed from a layer, some part of the chitin may fall off (if more than 10 percent falls off, the trilobite is considered substandard and can only be used as a donor). The missing, crumbled part of the chitin is restored using special materials that can be seen if you shine an ultraviolet flashlight on the sample – the restored parts will glow. If a small crack has been smeared on a trilobite, then the sample loses almost no value. But the presence of intact plastic elements significantly depreciates the value of the sample. In the late 90s and early XNUMXs, people really liked to fake the spikes on the cephalon Hoplolichas plautini, until this came up at one of the exhibitions in Germany. Then a lot of trilobites, bought for very decent money, were returned by collectors to dealers, and since then they have stopped counterfeiting spikes. By the way, trilobites of the genera Asaphus and Illaenus do not undergo donor restoration at all, it is simply unprofitable, the most they can have is smeared crumbling chitin, or donor eyes of Asaphus kowalewskii – they were unfortunately poorly preserved. To briefly summarize the above, it is still not worth taking Moroccan trilobites, because. the risks are too high, and when purchasing trilobites from the Leningrad region, use an ultraviolet lamp, or purchase only from trusted suppliers (well, do you understand who we mean?). Happy shopping, friends! And may the real trilobites be with you 🙂 How to determine the age of a fossil? How many thousands or millions of years ago did the found organism live? How was it determined which period the formation belonged to? Geologists and paleontologists have two main dating methods: relative and absolute. The relative method is faster but less accurate. Relative dating uses already studied organisms, rocks and formations. For absolute dating, a laboratory is needed to study the find. By knowing the rate of decay of certain isotopes, and how much they decayed, we can fairly accurately determine the age of the organism or, more often, the rock in which it was found.

Relative method

The relative dating method is used when we know what we found and where. For example, we found a Tyrannosaurus rex tooth from the Hell Creek Formation. We do not need a laboratory to determine the exact age. We know when Tyrannosaurus rex lived and what period the Hell Creek Formation covers. But what to do if we have unexplored layers of rocks in front of us? In this case, so-called index fossils come to our aid. As a rule, these are specific organisms characteristic only of a certain period. Their age has already been determined by the absolute method. For example, brachiopods are valuable index fossils. Thanks to these invertebrates, we can determine not only the age of the rocks, but also the physical and geographical situation of the studied area. Thus, brachiopods found in 2014 on the banks of the Shiderty River told researchers that the age of the rocks was 345-400 million years, and the area was a warm sea with an average annual temperature of +5 to +25 degrees. Accordingly, the remains of other organisms found in the same layer as these brachiopods would also date back to the Devonian period. You can also use multiple indexes. Let’s imagine that we found a formation in which the brachiopods already known to us were preserved, with an age of 345-400 million years. In the same layers, next to brachiopods, we also find trilobites dating back to 410-390 million years ago. Simple arithmetic and we get the age of the formation from 400 to 390 million years. Also in the relative dating method it is worth remembering that the layers are applied sequentially. If we find fossils whose age we know, the layer above them will be younger, and the layer below it will be older.

Absolute method

Accurate determination of the age of fossils using the absolute dating method occurs using radiometry (radioisotope dating). Radiometry uses various radioactive isotopes, which work like clockwork. The uniform radioactive decay of isotopes can help us establish very precise ages for rocks from different geological eras. From the tools of our ancestors to the exact age of the planet itself. Most often, volcanic rocks, which are layered, help us determine the age of a fossil. By dating the volcanic layers below and above the fossil, we can tell the age of the remains found. The difficulty of the absolute method is that we cannot always find the isotope we need for a particular era. For example, when it comes to radioisotope dating, the first thing that comes to mind is radiocarbon dating. But it is very rarely used for dating fossils, its degree of accuracy is good for remains younger than 60 years. During this time, the C-000 isotope goes through 14 half-life cycles and decreases by 10 times. Half-life is the time during which half of a certain amount of isotopes decays. For the C-14 isotope, this is 5730 ± 40 years. That is, in 5730 years the isotope decays by half, in another 5730 years the remaining part of it decays by half, and so on. But what if we need to set the age to millions and hundreds of millions of years? There are other methods for this that use other isotopes. Uranium-lead the analysis involves the use of uranium isotopes: uranium-235 or uranium-238. The uranium-lead method is one of the oldest and best-studied methods for dating rocks hundreds of millions and billions of years old. The accuracy of this method is very high; for rocks 2 billion years old the error will be ± 2 million years (0,1%). One of the advantages of this method is its large age coverage. The half-life of uranium-235 with its transformation into lead-207 has a period of 700 million years, and that of uranium-238 into lead-206 has a period of 4,5 billion years. Sometimes the uranium-thorium-lead method with the thorium-232 isotope is used. The transformation of thorium-232 into lead-208 has a period of 14 billion years. Lead-lead The analysis examines the presence of three isotopes in rocks: lead-206, lead-207 and lead-204. This method is used to determine the age of meteorites and rocks that have lost the isotopes uranium-235 and uranium-238. Thanks to the lead-lead method, the age of the Earth was determined. The ratio of lead-207 to lead-206, as a result of the decay of uranium-235 and uranium-238, respectively, in Earth rocks and meteorites suggested the date of the planet’s formation. To date, the most accurate figure is 4.567.200.000 ± 600.000 years. Potassium-argon The good thing about the analysis is that potassium is found in many materials: mica, clay minerals, volcanic sediments, evaporites. Because of its long half-life, the potassium-argon method is used to date fossils over 100 years old. These are not all the ways to determine the age of a find, both relative and absolute. We have no difficulty when it comes to dating a fossil whose species and location are known. It is more difficult when the sample has lost or does not have accurate data on the location of discovery. This applies to old museum exhibits, finds from amateur paleontologists, or fossils recovered from black diggers.

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