Malachite green in eels and fish imported from China and Taiwan. In 2006, the United States Food and Drug Administration (FDA) detected malachite green in seafood imported from China, among others, where the substance is also banned for use in aquaculture. In June 2007, the FDA blocked the importation of several varieties of seafood due to continued malachite green contamination. The substance has been banned in the United States since 1983 in food-related applications. It is banned in the UK, also. Animals metabolize malachite green to its leuco form. Being lipophillic (the leuco form has a log "P" of 5.70), the metabolite
Mineral the sample reflecting different colours as it is turned, while pleochroism describes the change in colour as light passes through a mineral in a different orientation. Iridescence is a variety of the play of colours where light scatters off a coating on the surface of crystal, cleavage planes, or off layers having minor gradations in chemistry. In contrast, the play of colours in opal is caused by light refracting from ordered microscopic silica spheres within its physical structure. Chatoyancy ("cat's eye") is the wavy banding of colour that is observed as the sample is rotated; asterism, a variety of chatoyancy,