At a gemology research center, two clear, colorless minerals were brought in for testing. Both formed six-sided crystals and looked nearly identical, which initially suggested they might share the same properties. Scratch testing revealed a sharp contrast: one fractured easily under a knife blade, while the other resisted scratching even from a steel file. This unexpected difference led the team to consider how internal bonding might explain the variation in hardness despite their similar outward appearance. Which conclusion best explains the difference in hardness between the two minerals?
Answer
A
Because both minerals form six-sided crystals, they should belong to the same classification group regardless of hardness.
B
Minerals with similar external features usually have the same hardness, so these results are inconsistent with expectations.
C
The mineral that fractured easily likely has weaker bonds between layers, while the resistant one has stronger bonding throughout.
D
Differences in hardness are mainly controlled by visible traits such as clarity and luster rather than atomic bonding.
Explanation
Hardness depends largely on how strongly atoms are bonded and how easily the structure can be disrupted. A mineral that is scratched or fractured easily has weaker bonding in the relevant directions, while one that resists a steel file has stronger bonding. Similar six-sided crystal shapes and colorless appearance do not guarantee equal hardness, so choice C best explains the contrast.
AI-written and checked against the verified answer.