This is elemental Mn, they are bits of sheet that is formed when Mn is refined though the electrolytic process, smooth one side and rough the other. The melting point of this element is 1246 degrees c and it has a density of 7.21.
This element is very hard yet brittle. This sample is supplied in a small bag and will be posted in an envelope.
Any questions please feel free to ask. and note the photos are stock photos of my actual stock and your sample may vary slightly.
Note that manganese is a toxic element, always wear gloves, dust mask and goggles and take care when handling and take great care not to inhale any dust. Please store safely away from kids etc.