Final answer:
Streak is the color of a mineral in powdered form, which is observed by scratching the mineral across a ceramic streak plate. It is more reliable for rock identification compared to color because it remains consistent and is not affected by impurities.
Step-by-step explanation:
Streak is the color of a mineral in powdered form, which can be observed by scratching the mineral across a ceramic streak plate. Unlike color, which can vary due to impurities in the chemical composition, streak remains consistent because impurities do not significantly affect the absorption of light in the powdered form. Streak is considered more reliable for rock identification, especially for metallic minerals, because most other minerals have the same streak color as the hand-sample color or a white streak.