Final answer:
The mineral is most likely to be a nonmetallic mineral because it has a white streak and a relatively low specific gravity of 2.8.
Step-by-step explanation:
The mineral is most likely to be a nonmetallic mineral. The reason for this is that the mineral's streak is white. Streak is the color of a mineral in powdered form, and most metallic minerals have a streak color that corresponds to their hand-sample color. Therefore, a mineral with a white streak is more likely to be nonmetallic.
Additionally, the specific gravity of the mineral is 2.8. Specific gravity is the ratio of the density of a substance to the density of a reference substance, usually water. Metallic minerals generally have higher specific gravities than nonmetallic minerals. Since the specific gravity of the unknown mineral is relatively low, it further supports the conclusion that it is a nonmetallic mineral.
In conclusion, based on the white streak and low specific gravity, the unknown mineral is most likely a nonmetallic mineral.