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What is Malachite?
Malachite is a green copper carbonate hydroxide mineral with a chemical composition of Cu2(CO3)(OH)2. It was one of the first ores used to produce copper metal. It is of minor importance today as an ore of copper because it is usually found in small quantities and can be sold for higher prices for other types of use. Malachite has been…
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Uses of Azurite
While azurite is not an extremely abundant mineral and is rarely found in large deposits, it has been used in a number of ways. Some of these are explained below. Copper Prospecting and Mining Geologists know that abundant azurite is often found in the rocks above deposits of copper ore. That enables them to use azurite as…
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Physical Properties of Azurite
The most diagnostic property of azurite is it distinctive deep blue color. It is also soft with a Mohs hardness of only 3.5 to 4. It contains copper, which gives its blue color and a specific gravity of 3.7 to 3.9, which is exceptionally high for a non-metallic mineral. Azurite is a carbonate mineral and produces a…
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Geologic Occurrence
Azurite is a secondary mineral that usually forms when carbon-dioxide-laden waters descend into the Earth and react with subsurface copper ores. The carbonic acid of these waters dissolves small amounts of copper from the ore. The dissolved copper is transported with the water until it reaches a new geochemical environment. This new environment could be a location where water…
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What is Azurite?
Azurite is a copper carbonate hydroxide mineral with a chemical composition of Cu3(CO3)2(OH)2. It is best known for its characteristic deep blue to violet-blue color. The blue color, known as “azure,” is like the deep blue evening skies often seen above deserts and winter landscapes. Azurite is not a common or abundant mineral, but it is beautiful…
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Anyone Can Own Ametrine
If you search online or go to a jewelry store that has a nice selection of colored stone jewelry, you might find a few pieces of ametrine for sale. The price is usually inexpensive when compared to other stones of similar size and beauty – certainly less expensive than bicolor tourmaline. Almost anyone who can…
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Synthetic / Treatment-Created “Ametrine”
Laboratory experiments in 1981 determined that heat and irradiation can be used to convert natural amethyst into a bicolor material that has an appearance similar to natural ametrine. This process is costly to do well and is not known to have produced a significant amount of treatment-created “ametrine.” In 1994 a laboratory in Russia began…
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Ametrine Gemstones
A crystal containing both amethyst and citrine in contact with one another can be called “ametrine.” These crystals usually contain zones of clear quartz, amethyst, and citrine. When these crystals are cut into pieces that are appropriately sized for faceting gemstones, only a portion of the stones will be ametrine. The remainder will be amethyst,…
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History of Ametrine
According to legend, the Ayoreo Indian tribe of eastern Bolivia knew about the bicolor quartz crystals over 500 years ago. Perhaps the earliest formal documentation of natural quartz crystals with zonal coloring of purple and yellow is in a 1925 issue of American Mineralogist. These were basal sections of quartz crystals with color sectors alternating…
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What Gives Ametrine Its Color?
The colors of amethyst and citrine are produced by iron impurities with different oxidation states within the quartz. Purple is thought to be produced by Fe3+ that is oxidized to Fe4+ by natural radiation emitted by the decay of potassium-40 in nearby rocks. The golden-yellow is thought to be produced by Fe3+. If a well-formed ametrine crystal…