Arsenic is a a trivalent and pentavalent, solid, poisonous element that is commonly metallic steel- gray, crystalline and brittle. It is used in medicine and in the manufacture of electronic components. It has a garlicky odour but otherwise it is difficult to distinguish from antimony. It is a relatively rare mineral found in veins in crystalline rocks associated with silver, cobalt, or nickel ores. It has the symbol As. Arsenic tablets were formerly worn as protection against the plague.
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