Amazonite Gemstones
The most common minerals in the world are the feldspars, which make up nearly 60% of the earth’s crust. Given the ubiquity of feldspar, it is somewhat surprising that there are so few feldspar gemstones. By contrast, another very common mineral, quartz, has as least a dozen well-known gemstone varieties, including amethyst, citrine, tiger’s eye, chalcedony and agate.
There are two main subgroups of feldspar that produce gem-quality material: the potassium feldspars and the plagioclases, a series that ranges from calcium to sodium feldspars. Among the feldspar gemstones are moonstone, orthoclase, amazonite, andesine, labradorite and sunstone.
Amazonite, moonstone and orthoclase are all potassium feldspars. They have a hardness of 6 to 6.5 on the Mohs scale, and a vitreous luster. Moonstone is a very well-known gemstone, but orthoclase and amazonite are not.
Amazonite is a gemstone variety of green microcline. It is named after the Amazon river in Brazil, though surprisingly no deposits have been found in that location. The story is that some green stones were once found in the Amazon river area, but mineralogists believe that there is no green feldspar there, though there are deposits elsewhere in Brazil.
The lively green or blue-green color of amazonite can be quite beautiful when polished. Since amazonite is an opaque stone, it is usually fashioned as cabochons. It is a medium-hard material, rating 6 to 6.5 on the Mohs scale, so it is not ideally suited to rings. But it makes very attractive earrings and pendants.
For many years,
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