![]() These fluids flow along sub-surface fractures, where galena and other minerals may be deposited to form vein deposits. Lead deposits form from hot, aqueous (or hydrothermal) fluids generated within the earth. Cerussite (PbCO3) and anglesite (PbSO4) commonly occur in the near-surface weathered or oxidised zone of lead orebodies. The main lead mineral is galena (PbS), which contains 86.6% lead by mass. Modern paints now contain titanium dioxide instead, a safe mineral sands product. Prior to the 1970s, most house paint contained lead, so people renovating old houses are advised to wear face-masks when sanding or scraping the old paint off walls. However, lead is highly toxic so many uses of lead have been discontinued and the major use of lead today is in batteries for motor vehicles and in communications. Many 15th and 16th century buildings had lead roofs (including Westminster Abbey and St Paul's Cathedral which still stand today) and during the Great Fire of London in 1666, the gutters were running with molten lead. The Japanese added lead to bronze to increase fluidity. The ancient Phoenicians mined and smelted lead in Cyprus, Sardinia and Spain. During the Middle Ages, lead was among the main exports of England. The Romans gladiators even used lead knuckle dusters. Roman baths in Bath, England, were lined with lead and fed by lead pipes from hot mineral springs. The Romans had an elaborate water distribution system of lead aqueducts. Lead pipes, water tanks, coins and weights for fishing nets were used in ancient Egypt and the Hanging Gardens of Babylon were floored with soldered sheets of lead. Its widespread occurrence, relatively simple extraction and combination of desirable properties have made it useful to humans since at least 5000 BC. Lead is one of the oldest metals known to humans. In producing high-quality crystal glassware, stained-glass window 'frames', colour lenses, pottery glazes and as a 'red lead' undercoat on bridges and other exposed steel structures.Īmmunition, ceramics, UV barrier in PVC products, and to minimise sulphur gas emissions by industry. ![]() However, due to lead's toxicity, this usage is decreasing. Lead's low melting point makes it an excellent solder, often alloyed with tin. Lead's density makes it useful as a weight, such as for curtains, SCUBA divers and yacht keels (fishing sinkers tend not to be made from lead these days). Lead flashings (where roofs meet walls or chimneys) stop leaks, resist wind lift and do not corrode. Lead's corrosion resistance makes it ideal to line containers and pipes for storing and carrying corrosive chemicals. Lead's ductility and resistance to corrosion makes it an excellent sheath around electrical cables, especially under the sea. Even whole buildings can be mounted on lead to reduce vibration problems. Lead's density and softness also makes it an excellent absorber of sound, so thin lead sheets are laminated onto building materials such as plywood, aluminium or steel to provide sound insulation. It is also in computer screens and TV tubes to absorb radiation. These batteries provide as much power in five hours as the average home uses in a year.Īs lead is very dense and highly absorbent, it is used as a radiation shield around X-ray, radiotherapy treatment, and nuclear equipment. Non-nuclear submarines rely on a bank of lead-acid batteries for extra power and for ballast to keep them upright. Batteries are important in hospitals and communication centres needing a back-up supply in case of power failures and in solar and wind power systems (to store the energy). The major use for lead is in lead-acid batteries to store power in cars, wheelchairs, lift trucks, baggage loaders, even golf carts and submarines. Lead has good electrical conductivity and resistance to corrosion.
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