Answer:
Metallic structure
Explanation:
They have a high melting point due to the strong forces of attraction between the positive ions (cations) and the delocalised electrons. Moreover, they conduct electricity due to the sea of delocalised electrons.
<em>[Extra: It could be an ionic compound since they also have a high melting point, however they only conduct electricity in liquid or aqeouus state.]</em>
<span>The layer of rock above it might contain the fossil of a fish as, according to the law of faunal successsion, this was the first animal to evolve after shelled organisms. In sedimentary rock, animals that evolved later could only be found in layers above those from an earlier time.</span>
Grinding as it’s a physical not chemical change :)
