Zinc

Zinc is a chemical element with symbol Zn and atomic number 30. It is the first element of group 12 of the periodic table. In some respects zinc is chemically similar to magnesium: its ion is of similar size and its only common oxidation state is +2. Zinc is the 24th most abundant element in Earth's crust and has five stable isotopes. The most common zinc ore is sphalerite (zinc blende), a zinc sulfide mineral. The largest mineable amounts are found in Australia, Asia, and the United States. Zinc production includes froth flotation of the ore, roasting, and final extraction using electricity (electrowinning).

Brass, which is an alloy of copper and zinc, has been used since at least the 10th century BC in Judea and by the 7th century BC in Ancient Greece. Zinc metal was not produced on a large scale until the 12th century in India and was unknown to Europe until the end of the 16th century. The mines of Rajasthan have given definite evidence of zinc production going back to the 6th century BC. To date, the oldest evidence of pure zinc comes from Zawar, in Rajasthan, as early as the 9th century AD when a distillation process was employed to make pure zinc.Alchemists burned zinc in air to form what they called "philosopher's wool" or "white snow".

Metal roof

A metal roof is a roofing system made from metal piece, or tiles. It is a component of the building envelope.

Metal roofs protect buildings.

In the United States, metal comprises 10% of the overall residential re-roofing market.

History

Copper has played a significant role in architecture for thousands of years (see: Copper in architecture). In the 3rd Century B.C., copper roof shingles were installed atop of the Loha Maha Paya Temple in Sri Lanka. And the Romans used copper as roof covering for the Pantheon in 27 B.C. Centuries later, copper and its alloys were integral in European medieval architecture. The copper roof of St. Mary's Cathedral, Hildesheim, installed in 1280 A.D., survived until it's destruction during bombings in World War 2. And the roof at Kronborg, one of northern Europe's most important Renaissance castles (immortalized as Elsinore Castle in Shakespeare’s Hamlet) was installed in the 1585 A.D. The copper on the tower was renovated in 2009.

Earlier metal roofing was a sheeting in the form of corrugated galvanized steel and still find applications today in parts of the developing world. In addition, colour-coated steel roofs are popular in some of the Nordic countries such as Finland and Sweden.

Zinc (disambiguation)

Zinc is a metallic chemical element.

Zinc may also refer to: