Not one mineral can be identified by just one property because there are many minerals that appear to be similar.
A hard mineral to identify is Quartz because it appears to look like other minerals at the first glance.
An easy mineral to identify is Sulfur because of it's smell. Sulfur smells like rotten eggs!
The most useful physical property was hardness because it narrowed down the minerals from 16 to three or four.
The least useful property in identifying minerals was color because many minerals appear in an array of color (e.g. Calcite).
The two minerals that were the hardest to tell apart were Pyroxene and Olivine. I eventually was able to distinguish them by hardness.
The streak test is better than color for identifying a mineral because it is more specific. A streak test also help to determine the hardness of a mineral!