Calamine (mineral) crystallographically quite distinct, the two minerals exhibit similar massive or botryoidal external form and are not readily distinguished without detailed chemical or physical analysis. The first person to separate the minerals was the British chemist and mineralogist James Smithson in 1803. In the mining industry the term calamine has been historically used to refer to both minerals indiscriminately. In mineralogy calamine is no longer considered a valid term. It has been replaced by smithsonite and hemimorphite in order to distinguish it from the pinkish mixture of zinc oxide (ZnO) and iron(III) oxide (FeO) used in calamine lotion. In the 16th
Metallic mean Metallic mean The metallic means or silver means (also ratios or constants) of the successive natural numbers are the continued fractions:formula_1 The golden ratio (1.618...) is the metallic mean between 1 and 2, while the silver ratio (2.414...) is the metallic mean between 2 and 3. The term "bronze ratio" (3.303...), or terms using other names of metals (such as copper or nickel), are occasionally used to name subsequent metallic means. The values of the first ten metallic means are shown at right. Notice that each metallic mean is a root of the simple quadratic equation: formula_2, where formula_3 is