DescriptionCorundum (Pennsylvania, USA) 5.jpg English: (cut surface; ~7.5 centimeters across at its widest) A mineral is a naturally-occurring, solid,...
DescriptionCorundum (Pennsylvania, USA) 1.jpg English: (~7.5 centimeters across at its widest) A mineral is a naturally-occurring, solid, inorganic, crystalline...
DescriptionCorundum (Pennsylvania, USA) 2.jpg English: (~7.5 centimeters across at its widest) A mineral is a naturally-occurring, solid, inorganic, crystalline...
DescriptionCorundum (Pennsylvania, USA) 6.jpg English: (~7.5 centimeters across at its widest) A mineral is a naturally-occurring, solid, inorganic, crystalline...
DescriptionCorundum (Pennsylvania, USA) 3.jpg English: (~7.5 centimeters across at its widest) A mineral is a naturally-occurring, solid, inorganic, crystalline...
DescriptionCorundum (Pennsylvania, USA) 4.jpg English: (cut surface; ~7.5 centimeters across at its widest) A mineral is a naturally-occurring, solid,...
Sim popular-mechanics 1910-06 13 6 (page 26 crop).jpg...
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