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English Answer:
The metal foil commonly used for wrapping chocolate is aluminum. Aluminum foil is favored due to its excellent barrier properties against light, oxygen, and moisture, which are critical in maintaining the quality and freshness of chocolate. It is also lightweight, flexible, and can be easily formed around the contours of the chocolate. Additionally, aluminum has good thermal conductivity, which can be beneficial during the tempering process of chocolate making. It's important to note that the aluminum foil used for chocolate is typically very thin and may be coated or laminated with other materials to enhance its barrier properties or to make it heat-sealable.

中文回答：
用于包裹巧克力的金属箔通常是铝箔。由于铝箔对光、氧气和水分具有极好的阻隔性能，这对于保持巧克力的质量和新鲜度至关重要。它也是轻质的、灵活的，并且可以很容易地围绕巧克力的轮廓成型。此外，铝具有良好的热传导性，这在巧克力制造过程中的调温过程中可能是有益的。需要注意的是，用于巧克力的铝箔通常非常薄，并且可能涂有或其他材料层压以增强其阻隔性能或使其具有热封性。

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Aluminium foil (or aluminum foil), often referred to with the misnomer tin foil, is aluminium prepared in thin metal leaves with a thickness less than 0.2 mm (7.9 mils); thinner gauges down to 6 micrometres (0.24 mils) are also commonly used.read more >>