The inevitable bumps and scrapes as gold bars are moved around mean dust and slivers of the metal which are sucked up and recycled.

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Indium is leached from slag and dust of zinc production and the metal further purified by electrolysis.

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There's an important distinction between these two types of objects: Comets are mostly water, ice and dust, while asteroids are mostly rock or metal.

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Once inside, he stared in dismay at rows of metal shelves, stacked with thousands of documents, all cloaked in layers of dirt and dust.

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