The correct answers are:
- luster;
- streak;
The minerals can be classified by their unique physical properties, at least in most cases, with the luster, streak, hardness, specific gravity, color, tenacity, cleavage, and fracture, being used for identification.
The luster essentially is the how the mineral reflects the light, with the terms metallic and non-metallic being used usually, while for the few minerals that do not reflect the light are used terms such as ''dull'' or ''earthy'' minerals.
The streak is the color of the powdered mineral. In most cases this a more precis method than using the color of the whole mineral piece itself.
