A second type of market failure occurs when no market exist to create a price for important social goods. Endangered species, scenic vistas, rare plants and animals, and biodiversity are just some environmental goods that typically are not traded on open markets(when they are,it often is in ways that seriously threaten their viability as when rhinoceros horns, tiger claws, elephant tusks, and mahogany trees are sold on black market). Public goods such as clean air and ocean fisheries also have no eatablished market price. With no established exchange value, the market approach cannot even pretend to achieve its own goals of adequately meeting consumer demand. Markets alone fail to guarantee that such important public goods are preserved and protected.