In more modern times the Malay Straits and the tin-fields of Nigeria have attracted the tin-seeker else¬where, but the Cornish miner is still sought even in these remote quarters of the globe.

The only important ore of tin is tinstone or cassi-terite, which occurs in granite rocks of coarse texture. It is widely distributed, but is only found in paying quantities where the heavy metal has been washed from its granite source in the process of erosion and weather¬ing, and has collected in gravel and sand as a placer deposit termed ” stream tin.” Tin mines, wherever they exist, have been discovered by tracing these stream deposits back to their source in some parent granite or associated rock.

For extracting the tin from the tinstone the crude ore is pounded and the lighter gangue washed away with water. The washed ore is then roasted to remove the arsenic, sulphur and other impurities still remaining, the purified ore, known as ” black tin,” afterwards going to the furnace.
An ingot of pure tin is almost pure white. A slight tinge of blue is the only discolouring. It is lustrous, soft and elastic, and does not tarnish upon exposure to the air. Its crystalline nature you can detect by the characteristic crackling noise a sheet or bar makes when bent. When rubbed it gives a peculiar odour; at a temperature of 200° it becomes brittle, at 228° it fuses, and when raised to a white heat it enters into ebullition and burns with a brilliant white light.
Good ore should yield 6 per cent, black oxide containing 78 per cent, of metal.