what is the history behind this latter mentioned construction product?
Obsidian mirrors of Anatolia was found around 6000 BC, mirrors of polished copper found in Mesopotamia is from 4000 BC, and polished stone mirrors from Central and South America date around 2000 BC onwards.
Mirror
Examples of obsidian mirrors found in Anatolia (modern-day Turkey) have been dated to around 6000 BC. Mirrors of polished copper were crafted in Mesopotamia from 4000 BC, and in ancient Egypt from around 3000 BC. Polished stone mirrors from Central and South America date from around 2000 BC onwards.
what are heavy metals? Metals with relatively high densities and atomic weights. what is its biological role? Period 4 heavy metals are required for certain biological processes. what are its uses? Iron accounts for 90% of all refined metals and platinum accounts for 20% of all consumer goods. what are the exposure sources? Mining and industrial wastes, vehicle emissions, etc. what is the origin and use of the term? Heaviness was noticed in prehistory and early use of the term "heavy metal" dates from 1817. who was behind its discovery? UNANSWERABLE what is its toxicity? Assumed to be highly toxic or damaging to the environment. what is its colouring and optics? Colours of glass, ceramic glazes, etc are produced by chromium, manganese, etc. and high reflectivity of some heavy metals is important in the construction of mirrors.
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Mirror [SEP] Prehistory
The first mirrors used by humans were most likely pools of dark, still water, or water collected in a primitive vessel of some sort. The requirements for making a good mirror are a surface with a very high degree of flatness (preferably but not necessarily with high reflectivity), and a surface roughness smaller than the wavelength of the light. 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. Mirrors of polished copper were crafted in Mesopotamia from 4000 BC, and in ancient Egypt from around 3000 BC.