Background | Name | Sources | Uses | Substitutes and Alternative Sources
Tin has been known from ancient times. Ancient peoples found that heating the tin mineral cassiterite (sometimes found in streams as nuggets) in a charcoal fire, they could produce the silvery, soft metal we know as tin.
Tin is a silvery-white metallic element with atomic number 50. Tin is malleable, meaning it is easily shaped by hammering. Pure tin also has a relatively low melting point, easily attainable in a wood fire, and is therefore easy to melt and cast in a clay mold. Tin is stable in air and water, meaning it does not oxidize or react easily . When pure tin is bent rapidly, it makes a peculiar squealing noise: this is called the “tin cry.”
The ancients found tin to be too soft to be of much use for other than decorative objects, and the use of pure tin in ancient times was restricted to mirrors, clasps, and decorative items. Some coins have been minted of tin, but the coins wear and bend rapidly. However, when mixed (alloyed) with copper, another metal which could be found in a nearly pure state in nature, then a new and much harder alloy resulted: bronze. This discovery marked the beginning of the historical period known as The Bronze Age. The advent of the Bronze Age, with the use of bronze spears, arrowheads, knives, sickles, and scythes, greatly enhanced the efficiency of hunters and farmers.
The most important ore mineral of tin, cassiterite (tin dioxide, SnO2) forms in high-temperature veins, usually related to igneous rocks such as granites and rhyolites. It is often found in association with tungsten minerals. When rocks containing cassiterite are weathered (decomposed by the action of surficial waters and oxidation), the cassiterite tends to remain intact, and eventually is concentrated in streams to form “placer” deposits, in a manner similar to gold nuggets in “placer” deposits. Ancient peoples recovered cassiterite from streams by panning, and even today panning or - more importantly - large-scale mechanical dredging of stream deposits and decomposed rock are a major means of producing cassiterite. Veins with a high enough cassiterite content to mine underground occur in China, Bolivia, Peru, and a few other countries.