Malachite green colored cation. The oxalate salt is also marketed. The anions have no effect on the color. The intense green color of the cation results from a strong absorption band at 621 nm (extinction coefficient of ). Malachite green is prepared by the condensation of benzaldehyde and dimethylaniline to give leuco malachite green (LMG): Second, this colorless leuco compound, a relative of triphenylmethane, is oxidized to the cation that is MG: A typical oxidizing agent is manganese dioxide. Hydrolysis of MG gives an alcohol: This alcohol is important because it, not MG, traverses cell membranes. Once inside the cell, it is
Mineral or red in hand sample, but has a cherry-red to reddish-brown streak. Streak is more often distinctive for metallic minerals, in contrast to non-metallic minerals whose body colour is created by allochromatic elements. Streak testing is constrained by the hardness of the mineral, as those harder than 7 powder the "streak plate" instead. By definition, minerals have a characteristic atomic arrangement. Weakness in this crystalline structure causes planes of weakness, and the breakage of a mineral along such planes is termed cleavage. The quality of cleavage can be described based on how cleanly and easily the mineral breaks; common descriptors,