Cassiterite Gemstone Information

Cassiterite is a tin oxide (SnO2) and it is the primary ore of tin. Since early times and still to this day, cassiterite has been the most popular source for tin. The mineral name, 'cassiterite', originated from a Greek word meaning 'tin', 'kassiteros'. As a result, it is commonly referred to as the 'tin stone'. Though cassiterite is quite abundant in rough mineral form, transparent gemstone quality material is exceptionally rare.

Owing to its rarity, cassiterite is considered a collector's stone. Most cassiterite occurs brownish to black, but brighter colors can also occur depending on crystal impurities. There is also a banded variety of cassiterite known as 'wood tin', which occurs with botryoidal, ring-like growths similar to agate quartz. Cassiterite's specific gravity (density) ranges from 6.7 to 7.1, making it one of the densest minerals on earth. It also has an extremely high refractive index, which results in exceptional fire and dispersion. Cassiterite also has an outstanding luster, often described as 'diamond-like' and submetallic. Since cassiterite has relatively good hardness and durability, it is perfectly suitable for most jewelry applications.

Cassiterite Mineral Occurrence

Cassiterite is a minor constituent of igneous rock and most often occurs in hydrothermal veins and pegmatites, typically granite intrusions. In many cases, cassiterite also forms alongside other minerals, such as tourmaline, fluorite, topaz and apatite. Cassiterite can also occur within hornfels of metamorphic rock, and deposits are often found in alluvial placer deposits, as rounded waterworn pebbles.

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	Cassiterite Gemstone Click to enlarge image

Cassiterite mineral deposits can be found in locations all over the world. The most significant sources include Australia, China, Malaysia, Indonesia, Thailand, Somalia, Namibia, Nigeria, the Congo, the Czech Republic, Russia, England (Cornwall), Spain, Bolivia, Mexico, Peru and the USA (California).

Bolivia is thought to have the best gem quality deposits and it is one of the few sources for 'wood tin'. In the late 1990s, both Russia and China produced very large, high quality transparent crystals.

Cassiterite Color

Cassiterite can occur in a variety of colors, ranging from colorless to brownish-black. The most common colors are dark-brown and near-black. Rarer colors include purple, wine and reddish to yellowish-brown.

Cassiterite Clarity and Luster

Cassiterite ranges in clarity from transparent to opaque material. Thin crystals possess slight translucency. Cassiterite has an extremely attractive imperfectly metallic, adamantine luster.

Cassiterite Cut and Shape

Cassiterite is primarily a collector's stone and it is most often faceted for display showcases. The most common cuts include emerald (octagon) step-cuts, as well as round, oval and cushion cuts. Many stones are free-form shapes finished with a light polish. Banded cassiterite (wood tin) is often cut en cabochon for jewelry.

Cassiterite Treatment

Cassiterite is not known to be treated or enhanced in any way.

Please refer to our Gemstone Glossary for details on gemology-related terms.

Vesuvianite - Idocrase

Cassiterite is a gemstone-quality tin oxide (SnO2). With regard to its chemical composition and formula, there are no directly related gemstones. However, there are a few minerals that have very similar compositions. There are also a variety of minerals that have a similar appearance. One of the most commonly confused materials is 'schorl', a brownish-black to black variety of tourmaline. Tourmaline, along with a variety of other minerals (topaz, calcite, and apatite), is often found together with cassiterite. Other minerals that are often confused with cassiterite include rutile, ilvaite, vesuvianite (idocrase) and columbite.

Most Popular, Similar Gems and Minerals:

Black tourmaline (schorl), idocrase (vesuvianite), rutile, calcite, apatite and hematite are the most popular mineral associations.

Lesser-Known, Similar Gems and Minerals:

Scheelite, sinhalite, limonite, muscovite, hedenbergite, arsenopyrite, scheelite, chromite, ilmenite, magnetite and uraninite are lesser-known mineral associations.

Cassiterite, also referred to as the 'tin stone', is a stone of divinity. It is a very powerful grounding stone, often used for deep meditation. Cassiterite is also very helpful for problem solving, especially in situations involving mathematics.

Cassiterite can increase intellectual abilities in its wearer, and it is thought to help balance the flow of chakra energies, especially the root chakra. One of the most powerful crystal beliefs is that cassiterite is believed to help ease suffering associated with death. Cassiterite can help guide the souls of the deceased to the eternal light and even after death, Cassiterite has great power, as it is believed to help with the process of reincarnation.

Cassiterite is a very common mineral, but it is rarely found in gemstone quality material. Cassiterite is not very well-known and it is not a stone you'll likely find in local jewelry stores. Cassiterite is considered a 'collector's stone', but unlike most collector stones, it is actually quite suitable for jewelry. Cassiterite has an attractive luster, as well as exceptional fire and brilliance. Cassiterite also has a relatively good hardness, which is comparable to quartz.

Most gem quality cassiterite is sourced from Bolivia. 'Wood tin' is very popular for jewelry-making, especially with the local jewelers of Bolivia. Cassiterite is best used as pendants, earrings, pins and brooches, but with care, they can also be worn in ring designs. Owed to its range of colors, cassiterite is suitable for both men and women.

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 diamond by weight in comparison.

Cassiterite does not have any special sensitivity to any chemicals or acid, nor does it have any distinct weakness for fracturing and cleavage. It is slightly softer than common quartz, so repolishing may be needed to retain its attractive luster and to remove surface scratches. Generally, the care and cleaning advice for cassiterite is very similar to that for quartz.

Like all gems, cassiterite can be easily scratched by harder materials, including topaz, sapphire and spinel. You can clean your stones using warm water, a soft cloth and a mild soap or detergent. Be sure to rinse well to remove soapy residue. Avoid the use of bleach or any other harsh chemicals. As with most gemstones, avoid extreme heat and temperature fluctuations. Do not use any ultrasonic cleaners or steamers and always take off any jewelry prior to exercising or playing any sports. When storing cassiterite, store them separately from other gems and jewelry. It is suggested to wrap your gemstones in a soft cloth and place them inside a fabric-lined box.