Final answer:
The streak color of a mineral is best tested by scratching the surface of the mineral with another mineral. This involves rubbing the mineral on a streak plate made of unglazed porcelain.
Step-by-step explanation:
The streak color of a mineral is best tested by scratching the surface of the mineral with another mineral. This method involves rubbing the mineral on a streak plate made of unglazed porcelain, which leaves behind a powdered streak of the mineral. The color of this streak can differ from the mineral's actual color because impurities do not significantly affect the absorption of light in powdered form. By observing the streak color, you can gain valuable information about the mineral's identity.