How to distinguish serpentine from malachite?
Justification. Since its discovery, malachite has not been considered a rare stone, but increased demand has led to the depletion of most deposits, and counterfeits are increasingly found on the markets [1, 2]. Goal — demonstration of methods for determining the naturalness of malachite and popularization of knowledge about the variability of fakes and imitations. Methods It is quite easy to identify fake malachite. A series of simple manipulations will allow you to establish the naturalness of the stone. You need to pay attention to the following criteria:
- Mass of stone. This aspect allows you to identify plastic and glass counterfeits. It should be noted that malachite is heavier than most other natural minerals used to create an imitation of the real mineral.
- Dullness. Natural stone does not shine through in the sun. It lacks transparency, the surface is matte, with little shine. A simple way to check is to shine a flashlight on the stone or raise it to the sun. If light passes through it, then this is a fake gem.
- Heterogeneity. Malachite mined in African countries has beautiful, even rings, but the patterns on two gems cannot match. The effect of similarity can be achieved only by making the stone yourself, in an attempt to realize its exact imitation. To check the gem, you need to examine the samples presented nearby. The pattern of the concentric rings will vary slightly, but will vary. If the gems are similar to each other, then this is a fake.
- Shades. The differences are present not only in the pattern, the color of the stone itself says a lot. The master will use various paints when creating an imitation of malachite. For example, a coil can be “touched” in order to sell it under the guise of malachite. This is a natural stone, but its price is much less. The key difference is the shade: malachite has a deep emerald green, while serpentine has a marsh color.
- If you have a stone and you doubt that it is real malachite, you can check the stone by the color of the line by scratching it (Fig. 1). To do this, however, you will have to ruin one bead. The color of the malachite streak will be green – from light turquoise to very dark green. The color of the pseudomalachite streak will always be lighter than the stone itself.
- The ammonia and acid test is one of the best tests to determine the authenticity of a stone. Most fakes can be visually distinguished, but high-quality and expensive imitations can be misleading. It is worth considering that experiments will lead to a change in the appearance of the stone, so you only need to work with the back part of the gem or jewelry. The first test involves applying a drop of ammonia to a small area of malachite (Figure 2). The area on natural stone will fade after a few minutes. The ammonia will turn blue. Sometimes you need to wait more than 5–7 minutes; even a natural gem is coated with varnish, which can prevent the drop from contacting the surface of the stone. The second test is to apply acid to the stone. You need to add lemon juice to warm water and then apply it to the gem. The surface should bubble if the malachite is genuine. The reaction time depends on the presence or absence of varnish.
Rice. 1. Determination of the color of malachite trait
Rice. 2. Ammonia test
Do not forget that malachite produced under artificial conditions passes the above-mentioned tests, since it has a similar chemical formula. Unfortunately, there are no methods for determining laboratory stones, so in this case you can only rely on the honesty of the seller.
Results. Verification tests have been proposed to determine the naturalness of a stone.
Conclusions. Buyer awareness of the different types of counterfeit and how to identify it will significantly reduce the number of cases of fraud involving counterfeit malachite.
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Justification. Since its discovery, malachite has not been considered a rare stone, but increased demand has led to the depletion of most deposits, and counterfeits are increasingly found on the markets [1, 2].
Goal — demonstration of methods for determining the naturalness of malachite and popularization of knowledge about the variability of fakes and imitations.
Methods It is quite easy to identify fake malachite. A series of simple manipulations will allow you to establish the naturalness of the stone. You need to pay attention to the following criteria:
- Mass of stone. This aspect allows you to identify plastic and glass counterfeits. It should be noted that malachite is heavier than most other natural minerals used to create an imitation of the real mineral.
- Dullness. Natural stone does not shine through in the sun. It lacks transparency, the surface is matte, with little shine. A simple way to check is to shine a flashlight on the stone or raise it to the sun. If light passes through it, then this is a fake gem.
- Heterogeneity. Malachite mined in African countries has beautiful, even rings, but the patterns on two gems cannot match. The effect of similarity can be achieved only by making the stone yourself, in an attempt to realize its exact imitation. To check the gem, you need to examine the samples presented nearby. The pattern of the concentric rings will vary slightly, but will vary. If the gems are similar to each other, then this is a fake.
- Shades. The differences are present not only in the pattern, the color of the stone itself says a lot. The master will use various paints when creating an imitation of malachite. For example, a coil can be “touched” in order to sell it under the guise of malachite. This is a natural stone, but its price is much less. The key difference is the shade: malachite has a deep emerald green, while serpentine has a marsh color.
- If you have a stone and you doubt that it is real malachite, you can check the stone by the color of the line by scratching it (Fig. 1). To do this, however, you will have to ruin one bead. The color of the malachite streak will be green – from light turquoise to very dark green. The color of the pseudomalachite streak will always be lighter than the stone itself.
- The ammonia and acid test is one of the best tests to determine the authenticity of a stone. Most fakes can be visually distinguished, but high-quality and expensive imitations can be misleading. It is worth considering that experiments will lead to a change in the appearance of the stone, so you only need to work with the back part of the gem or jewelry. The first test involves applying a drop of ammonia to a small area of malachite (Figure 2). The area on natural stone will fade after a few minutes. The ammonia will turn blue. Sometimes you need to wait more than 5–7 minutes; even a natural gem is coated with varnish, which can prevent the drop from contacting the surface of the stone. The second test is to apply acid to the stone. You need to add lemon juice to warm water and then apply it to the gem. The surface should bubble if the malachite is genuine. The reaction time depends on the presence or absence of varnish.
Rice. 1. Determination of the color of malachite trait
Rice. 2. Ammonia test
Do not forget that malachite produced under artificial conditions passes the above-mentioned tests, since it has a similar chemical formula. Unfortunately, there are no methods for determining laboratory stones, so in this case you can only rely on the honesty of the seller.
Results. Verification tests have been proposed to determine the naturalness of a stone.
Conclusions. Buyer awareness of the different types of counterfeit and how to identify it will significantly reduce the number of cases of fraud involving counterfeit malachite.
Malachite from the ancient Greek “malakos” is translated as “soft”. This mineral has been known to people since ancient times, as evidenced by historical finds. An oval malachite pendant, ten and a half thousand years old, was found during archaeological excavations in the territory of ancient Iraq in burial places of the Neolithic era. Another ancient artifact, malachite beads, was found in Israel near Jericho.
Description of the mineral malachite
Malachite is a mineral, a basic copper carbonate, similar in structure to the rosasite group. The chemical formula CuCO3(OH)2 of the malachite mineral contains: CuO – 71,9%, CO2 – 19,9%, H2O – 8,2%. The mineral is common in the oxidation zone of copper sulfide, polymetallic and copper-iron ore deposits adjacent to limestones, dolomites and calcareous shales. Thus, malachite contains copper and calcium.
Well-formed crystals are quite rare in nature and are always small with a columnar, lamellar, needle-like appearance in the shape of a faceted prism. The thermally unstable compound easily decomposes even with slight heating. Decomposition of the mineral malachite results in cleavage to form tufts, fuzzballs, spherocrystals, spherulites, spheroidolites and spheroidolite dendrites.
The rock is formed by the interaction of solutions of copper sulfates with carbonic or carbonate waters. Malachite also forms on the surface of ancient bronze and brass items that are discovered during archaeological excavations. If we talk about what minerals malachite consists of, then most often these are sulfide ores, usually consisting of chalcocite, chalcopyrite, bornite and covellite.
What color is the mineral malachite?
Malachite is a bright green mineral with a glassy luster, matte or silky surface, and a dull or translucent glow. The gem is distinguished by a rich color palette of all shades of green from emerald to grayish or yellow-green, sometimes smoothly turning into almost black.
Place of Birth
The main deposits of malachite are concentrated in Russia: in the Mednorudyansky and Gumeshevsky mines, in the Urals and Altai. Malachite deposits have also been discovered in Kazakhstan, Western Europe, Congo and Zaire.
Application
Malachite is rightfully considered one of the most beautiful minerals with a rich green color due to the presence of copper compounds. Despite its low hardness, malachite is widely used in jewelry. Various decorative items are also made from it: vases, table linings, caskets and other luxury items, cabochons for inlay into small jewelry. Thin plates of malachite decorate the columns of St. Isaac’s Cathedral in St. Petersburg. An amazingly beautiful huge antique malachite vase adorns the center of the hall of the Mineralogical Museum. A.E. Fersman.
Scientists have repeatedly tried to synthesize malachite. The earliest attempts to artificially create malachite powder date back to the early 70th century. Much later, in the early 1975s of the 1990th century, Leningrad scientists were finally able to synthesize malachite in laboratory conditions, indistinguishable from natural one. In XNUMX, the method was patented and introduced at the Ural Gems plant in Yekaterinburg, where artificial malachite was successfully produced for several years. Since the late XNUMXs, artificial malachite has been synthesized for jewelry purposes by the St. Petersburg company Etalon-Zhenavi.
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