Tin mining Dredging for ore off the islands shores has churned up sediment which has buried coral reefs where fish live and harmed the local fishing industry. This is despite a prohibition on mining in waters within four miles of Bangka’s shore. Tin mining Tin mining began early in the Bronze Age, as bronze is a copper-tin alloy. Tin is a relatively rare element in the Earth’s crust, with approximately 2 ppm (parts per million), compared to iron with 50,000 ppm. Tin extraction and use can be dated to the beginnings of the Bronze Age around 3000 BCE, when it was observed
Chinese sun and moon mirrors most (1 part tin per 1 part copper) for "metallic mirrors", namely, the "jiànsuì" 鑒燧 "mirror-igniter" alloy (Hirth 1907: 217-218). However, these ratios are based on Chinese numerology instead of practical metallurgy. Beyond about 32% the alloy becomes excessively brittle, and increasing tin content brings no further advantages of any kind; this the Han metallurgists evidently knew. Indeed they knew much more, for they almost always added up to 9% of lead, a constituent which greatly improved the casting properties. Han specular metal is truly white, reflects without tinning or silvering, resists scratching and corrosion well, and was admirably adapted