the color of the minerals. which minerals scratch other minerals. which minerals reflect light most strongly. the samples that feel smoothest to the touch.
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: To compare the hardness of different minerals, it would be BEST to find
Possibilities:
- the color of the minerals.
- which minerals scratch other minerals.
- which minerals reflect light most strongly.
- the samples that feel smoothest to the touch.

which minerals scratch other minerals.