There are two ways to remove coal from the ground: surface mining and underground mining. Surface mining is used when a coal seam is relatively close to the surface, usually within 200 feet. The first step in surface mining is to remove and store the soil and rock covering the coal (called the overburden).
Pearl oysters are not closely related to true oysters, being members of a distinct family, the feathered oysters (Pteriidae). Both cultured pearls and natural pearls can be extracted from pearl oysters, though other molluscs, such as the freshwater mussels, also yield pearls of commercial value.
Zinc Content Amount in Oysters. Oysters are a type of shellfish belonging to the bivalve mollusk family, which also includes mussels, cockles and scallops. They can are edible and can be consumed raw or cooked and are often ingredients in soups and sauces. Along with being a good source of iron, vitamin B-12 and selenium, oysters are a very rich source of the mineral zinc. Zinc is an essential trace mineral that is required by the body, but only in small amounts.