While some natural glass does exist in nature, such as black stone and talc, the vast majority of glass is fired by humans at high temperatures. As far as we know, the origin of glass dates back to the Bronze Age of Mesopotamia. About 4,000 years ago, humans began melting silica (sand or crushed stone) and mixing it with small amounts of limestone and soda ash. According to Pliny, the invention of glass was a happy accident: the Roman historian suggested that glass was accidentally acquired by Phoenician sailors in the course of a beach picnic, but since there were no flames at the time capable of reaching temperatures high enough to melt sand, this view is questionable. Contemporary historians believe that glass may have been discovered in the process of making ceramics or working metals. These two processes require higher firing temperatures and longer firing times than baking bread or roasted leg of lamb.
