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.
Oysters â Best known as aphrodisiacs, oysters are a rich source of zinc for hair growth. Just 3 ounces of this nutritious shellfish boast a whopping 493% of your daily allowance of zinc. Zinc also helps support the oil glands that fill the hair follicles with sebum maintaining moisture in hair and preventing dryness.