Mirror

The first mirrors used by people were most likely pools of dark, still water, or water collected in a primitive vessel of some sort. The earliest manufactured mirrors were pieces of polished stone such as obsidian, a naturally occurring volcanic glass. Examples of obsidian mirrors found in Anatolia (modern-day Turkey) have been dated to around 6000 BC. Polished stone mirrors from central and south America date from around 2000 BC onwards.[1] Mirrors of polished copper were crafted in Mesopotamia from 4000 BC,[1] and in ancient Egypt from around 3000 BC.[2] In China, bronze mirrors were manufactured from around 2000 BC.[3]

Metal-coated glass mirrors are said to have been invented in Sidon (modern-day Lebanon) in the first century AD,[4] and glass mirrors backed with gold leaf are mentioned by the Roman author Pliny in his Natural History, written in about 77 AD.[5] The Romans also developed a technique for creating crude mirrors by coating blown glass with molten lead.[6]

Reflecting parabolic mirrors were first described by the Arabian physicist, Ibn Sahl, in the 10th century[7]. Ibn al-Haytham discussed concave and convex mirrors in both cylindrical and spherical geometries,[8] carried out a number of experiments with mirrors, and solved the problem of finding the point on a convex mirror at which a ray coming from one point is reflected to another point.[9] By the 11th century, clear glass mirrors were being produced in Moorish Spain.[10]

Some time during the early Renaissance, European manufacturers perfected a superior method of coating glass with a tin-mercury amalgam. The exact date and location of the discovery is unknown, but in the 16th century, Venice, a city famed for its glass-making expertise, became a centre of mirror production using this new technique. Glass mirrors from this period were extremely expensive luxuries.[11] The Saint-Gobain factory, founded by royal initiative in France, was an important manufacturer, and Bohemian and German glass, often rather cheaper, was also important.