Smithsonite Gemstone Information
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About Smithsonite - History and Introduction
Smithsonite is a gemstone quality zinc carbonate (ZnCO3), sometimes referred to as "zinc spar". Although smithsonite is an important ore of zinc, it is rarely found in well-formed crystals. Most deposits of smithsonite are found in globular or botryoidal (grape-like) clusters with only a few localities known to produce large, pure crystals of smithsonite. Owing to the rarity of gem-quality crystals, smithsonite is one of the lesser-known gemstones. Thus, it is primarily sought after by gem collectors rather than by jewelry designers.
Smithsonite is actually one of two zinc-bearing minerals previously known as calamine (the other mineral is hemimorphite). For many years, smithsonite and hemimorphite were believed to be the same mineral. Originally, the name calamine was used only in reference to the mineral hemimorphite. However, later, in 1803, renowned British chemist and mineralogist, James Smithson (1765-1829) was the first to describe calamine as two distinct minerals - a zinc carbonate and a zinc silicate; and in 1832, Francois Sulpice Beudant named the zinc carbonate "smithsonite", in honor of James Smithson. The zinc silicate is considered to be the rarer of the two and was named hemimorphite.
Smithsonite is identified as a zinc carbonate and distinguished from closely related hemimorphite through its composition and crystal form. Smithsonite forms in the trigonal crystal system while hemimorphite, the zinc silicate, forms with orthorhombic crystals. Smithsonite has a hardness of 5 on the Mohs scale and a higher density than that of hemimorphite. Smithsonite is actually denser than most gemstones. In fact, its density is higher than both sapphire and ruby. Smithsonite can be easily mistaken for chrysoprase, but smithsonite is much softer and typically lighter in color.
Smithsonite typically forms as a secondary mineral in zinc-bearing ore deposits. It is sometimes found in other types of carbonate rock and is also occasionally known to pseudomorph into other minerals. Smithsonite is usually found in globular or botryoidal (grape-like) aggregate form, rather than in pure crystals. Some of the most significant deposits are found in Australia, Mexico, Namibia, Zambia, Italy, Greece, Spain and the United States (New Mexico).
Buying Smithsonite and Determining Smithsonite Value Back to Top
Smithsonite is typically found in varying shades of light-blue to blue, light-green to green, and is often mixed with green and blue turquoise hues. Color variations are widespread owing to varying amounts of zinc and other trace impurities. Green and blue smithsonite is colored by copper, while cobalt is known to result in pink and purple. Yellow is caused by cadmium and iron is responsible for brown to reddish colors.
Smithsonite Clarity and Luster
Smithsonite is typically translucent to opaque, with translucent materials being the most desirable. When polished, smithsonite's luster is vitreous, but in aggregate form, its luster is pearly and it is often banded.
Smithsonite Cut and Shape
Smithsonite is typically cut en cabochon to enhance its soft color and maximize its desirable luster. It is not often cut for jewelry owing to its softness and rarity. The most common shapes are those that tend to preserve the most rough crystal weight, such as oval and cushion shapes. However, other fancier shapes can be found, including marquise or pear shapes. Calibrated sizes and round stones are quite rare.
Smithsonite is not typically treated or enhanced in any way. However, some botryoidal aggregates may be surface-oiled to enhance luster.
||Zn[CO3] - Zinc carbonate
||Trigonal - rhombohedral
||Light-green, light-blue, pink
||5 on the Mohs scale
||1.621 to 1.849
||4.00 to 4.65
||Translucent to opaque
|Double Refraction or Birefringence:
||Blue-white, pink, brown
Please refer to our Gemstone Glossary for details of gemology-related terms.
Smithsonite is closely related to hemimorphite, and for many years, they were both known as 'calamine'. Gem-quality blue to green smithsonite with a pearly luster is sometimes referred to as 'bonamite' in the trade. Other popular names used by gem and mineral collectors include the following:
Dry bone ore - a porous smithsonite often found in a honeycomb shape.
Turkey fat ore - a botryoidal form of yellow smithsonite.
Cadmium smithsonite - a yellow to green smithsonite, colored by cadmium.
Copper smithsonite - a blue to green smithsonite, colored by traces of copper.
Smithsonite is also commonly associated with various other gemstone minerals such as malachite and azurite. Smithsonite may also pseudomorph into other minerals such as calcite or fluorite.
Smithsonite Metaphysical and Crystal Healing Properties Back to Top
Smithsonite is an excellent stone used for the relief of tension and stress; both physical and emotional. For those at their breaking point, or on the verge of a mental breakdown, smithsonite's gentle presence can help by acting as a stone of tranquility. It is believed to impart harmony around those who wear it. For many, smithsonite is a stone which brings out their 'inner-child' and it is often used to encourage feelings of joy and compassion. It is associated with the zodiacal signs of Pisces and Virgo, and is the planetary stone for Neptune. It is a stone associated with the element of water and is often used for the cycle of rebirth. Many even believe that smithsonite can treat problems of infertility.
Disclaimer: Metaphysical and Alternative Crystal Healing Powers and Properties are not to be taken as confirmed advice. Traditional, Ceremonial and Mythological Gemstone Lore is collected from various resources and does not represent the sole opinion of SETT Co., Ltd. This information is not to replace the advice of your doctor. Should you have any medical conditions, please see a licensed medical practitioner. GemSelect does not guarantee any claims or statements of healing or astrological birthstone powers and cannot be held liable under any circumstances.
Since smithsonite is one the rarer and lesser-known gems, it is primarily a collector's stone and not often used for jewelry designs. It is also rather soft and fragile for most types of jewelry, although it does have roughly the same hardness as opal or turquoise, both of which are often used for jewelry.
If wearing smithsonite, be sure to set stones into very well-protected mountings. Its use should be limited to jewelry that is less prone to wear and tear, such as earrings, pendants, pins or brooches. Smithsonite cabochons could be worn in rings, but these should be reserved for occasional wear.
Note: Buy colored gemstones by size and not by carat weight. Colored stones vary in size-to-weight ratio. Some stones are larger and others are smaller than diamonds by weight in comparison.
Smithsonite does not boast great fame, but its founder does. James Smithson was a brilliant chemist, mineralogist and an important scientist. He was also known as shrewd investor who amassed a considerable fortune throughout his lifetime. Upon his passing, his living will requested that his wealth be donated "to the United States of America, to found at Washington, an establishment for the increase and diffusion of knowledge among men." In 1846, through Smithson's donated fortune, the famous Smithsonian Institution was founded.
Smithsonite is rather soft and exhibits a brittle tenacity. It also has perfect cleavage, which requires special care to prevent splitting, chipping and fracturing. Due to its softness, it can be easily scratched by many other gemstones. Smithsonite is also considered to be porous and can be stained through the absorption of chemical or perfumes. Therefore, do not use any harsh chemicals or cleaner such as bleach or sulfuric acid when cleaning your smithsonite gemstones. Also avoid spraying perfume or hairspray around your gemstones. Like most gemstones, avoid the use of ultrasonic cleaners and steamers. You can clean smithsonite using a soft cloth or brush and warm soapy water. Always be sure to rinse well to remove any soapy residue.
Remove any smithsonite jewelry prior to exercising, playing sports or performing any household chores. When storing smithsonite, store it separately and away from other gems and jewelry. If possible, wrap your gems in a soft cloth and place them inside a fabric-lined jewelry box for extra protection.