The stroke color (short dash) referred to in mineralogy the color of the mineral powder that is used as a simple determination method for the differentiation of similar appearing externally minerals.
To get the line color of a mineral that is pressed against a rough, unglazed porcelain surface and then rubbed it along. The wear appears in a characteristic color, which can be very different from the color of the mineral. For example, the line of metallic gold finish "cat gold" ( pyrite ) black, as well as the most ores.
In idiochromatischen ( self colored ) minerals the stroke color is often similar to the mineral color. In allochromatischen ( strange colored ) minerals, however, the stroke color is mostly white. Colorless minerals always have a white line.
The dash panel has the Mohs hardness of 6 and thus corresponds to the hardness of example, orthoclase. Is a mineral harder than the dash panel, a small sample of the mineral ground in a mortar can (powdered ) and are ground on the reticle. For dark minerals a white, bright minerals for a black porcelain board is recommended.