A usually grayish, fine grained mineral substance composed of the metamorphosised compaction of any of clay, volcanic ash, and shale sediments
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Category: <span>S</span>
The enlargement of an adit, mine opening or trench by excavating layers of side from its sidewalls
The fused or partially fused concentrate of byproducts leftover from the smelting of metal
A metamorphic rock mass formed at the intersection of two large igneous masses
A white precious metal Symbol, Ag.
A period within the Paleozoic era, 440 to 400 million years ago
Settled concentrations of sediment usually under an aqueous body
An orthorhombic, trimorphous mineral, Al2SiO5
A mass of igneous rock intruding between older rock strata
An excavated area of a mine