Coloration of Minerals by Bob Jackson

In one of the many ongoing discourses, agreed-on primary distinguished physical characteristic of minerals are color, hardness, density (specific gravity), fracture/cleavage, chemical composition and morphology (crystal structure). There are additional physical attributes, of varying degrees of subtlety, which occasionally attract attention depending on availability of, and accessibility to expensive instrumentation (to the person who  possesses a hammer, everything appears to be nails). We will briefly look into  coloration, having previously considered hardness. Color in minerals is primarily caused by: principal cation constituents or by trace cationic impurities (cation means positively charged ion) or crystal structures distortion (e.g. smokey quartz) Absence of color is caused, more usually, by structural factors. Color is rarely, if ever, sufficient information to identify a mineral. Color’s utility stems chiefly from three observations: perceived color, lustre ( a kind of color quality) and streak (powder). The cation most likely to produce colors are in the transition element series. Consequently, it gets quite confusing since these elements tend to have multiple positive valance states ( frequently...