《天工开物·下篇·五金》
初得时拿来咬一下，是柔软的，采金的人有的偷偷把它吞进肚子里去也不会对人有伤害。
初得时咬之柔软，夫匠有吞窃腹中者亦不伤人。
When it was first obtained, it was taken and bitten. It was soft. Some gold miners secretly swallowed it into their stomachs without any harm to people.