Idiochromasy
With Idiochromasie (from the Greek idios : intrinsically and chroma : color) is referred to the intrinsic color of a substance. An idiochromatic substance is itself the coloring substance and is not colored by any other substance or by physical effects caused by its structure . Idiochromatic fabrics usually show a similar color in the line color, but lighter due to the roughened surface. Due to the strong color strength also in powders (line color), idiochromatic substances make up most of the color pigments . Many idiochromatic minerals can therefore be found in colorants .
Idiochromatic substances are for example yellow sulfur or auripigment , blue azurite or green malachite . In most idiochromatic substances, an element of the transition metals is the coloring element in the chromophore . Vanadium , chromium , manganese , iron , cobalt , nickel or copper are often found . Depending on the oxidation level and complex formation , these elements can show very different colors.
In contrast, corundum , for example, is allochromatic : in its pure state it is colorless. If it is contaminated with iron, it becomes a blue sapphire , if it is chromium it becomes a red ruby . Allochromatic fabrics also usually have a white line color.
A third group is formed by pseudochromatic substances, which owe their color to optical effects, in particular to interference in thin layers . Examples are the shimmering ammolite or the temper colors of the bornite .