Cassiterite For Sale

Cassiterite (also known as tinstone) is the primary ore of tin. When pure, cassiterite will be colorless, but in most cases impurities will result in brown or black crystals. It is typically found in hydrothermal veins and pegmatites in regions of granite intrusion. In the appropriate environment, it can also precipitate from volcanic gas.

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Lustrous Cassiterite Crystals On Quartz - Viloco Mine, Bolivia #192179

4.1" Lustrous Cassiterite Crystals On Quartz - Viloco Mine, Bolivia

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Cassiterite: The Primary Ore Of Tin

Cassiterite, with its striking luster and density, is the chief ore of tin (Sn) and has played a critical role in human history and industrial development. Known for its durability and high tin content, this mineral has been mined for thousands of years, especially in tin-rich regions across Asia, Europe, and Africa. Let’s explore cassiterite’s properties, formation, notable deposits, and the historical significance that makes it a valuable mineral.

Cassiterite is a tin oxide mineral that is generally found in colors ranging from brown and black to yellow, red, and even colorless in rare cases. Its high specific gravity (6.8–7.1) and brilliant, adamantine to submetallic luster make it easy to distinguish from other minerals. Cassiterite is also remarkably hard for an oxide mineral, rating between 6 and 7 on the Mohs scale, which contributes to its resistance to weathering and persistence in placer deposits.

It often forms as prismatic or stubby crystals with a diamond-like sheen. Its crystal habit can vary, but it is most commonly found as well-formed crystals in quartz veins or as rounded grains in sedimentary deposits. Black, opaque cassiterite is the most common form, but transparent crystals, sometimes called “tin stone,” are highly valued as collector specimens.

How Cassiterite Forms

Cassiterite forms primarily in high-temperature hydrothermal veins and pegmatites, where it crystallizes from molten rock or vapor-rich fluids rich in tin and silica. Tin-bearing granitic rocks are often the source of this mineral, as tin accumulates in magma chambers and later rises through cracks and fractures to cool and solidify.

In some areas, weathering processes further concentrate cassiterite in secondary deposits, known as placer deposits. Due to its density and resistance to weathering, cassiterite erodes from primary deposits, then accumulates in stream beds and alluvial sands. These placer deposits have historically been a significant source of tin, as cassiterite grains are relatively easy to separate from lighter materials using traditional mining techniques.

Notable Locations of Cassiterite Deposits

Cassiterite is found in tin-rich regions worldwide, with both primary and placer deposits contributing to global tin production:

Southeast Asia (Malaysia, Indonesia, and Thailand): Historically, this region has been a leading producer of tin, especially from extensive placer deposits. Cassiterite mining in Southeast Asia dates back several centuries, with the mineral being panned from riverbeds and coastal areas.

China: China is currently one of the largest producers of cassiterite, with significant primary deposits located in Yunnan and Guangxi provinces. These high-grade veins contribute substantially to the global tin supply.

Bolivia: Bolivia is known for its high-altitude cassiterite deposits in the Andes. Mining began in the early 20th century, and Bolivia remains one of the top cassiterite producers, with notable deposits in the Llallagua and Potosi districts.

Africa (Democratic Republic of Congo, Rwanda, Nigeria): Cassiterite is also abundant in Central and West Africa, with the mineral found in both primary and secondary deposits. The mineral is often mined in small-scale operations and has become a source of tin for local and international markets.

Cornwall, England: Cornwall was one of the earliest sources of cassiterite, with evidence of tin mining dating back over 2,000 years. Though production has declined, Cornwall’s rich mining history helped fuel early developments in metallurgy and mining technology.

Cassiterite is prized by mineral collectors, especially in its well-formed, transparent crystal form. Rare, gem-quality specimens, particularly those with clear, brown, or yellow coloration, are highly valued. The aesthetic appeal of cassiterite is further enhanced by its crystal shapes and luster, which make it an attractive addition to mineral collections. Specimens from locations such as China, Russia, and Bolivia are sought after for their clarity and size.

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Gemmy Cassiterite Crystal Cluster - Viloco Mine, Bolivia #192180

Gemmy Cassiterite Crystal - Rwanda #305626

Cassiterite: The Primary Ore Of Tin

How Cassiterite Forms

Notable Locations of Cassiterite Deposits

Featured Photos