Answer: Luster
Step-by-step explanation:
- A mineral is a natural solid that has a a definite chemical composition.
There are two kinds of minerals : metallic and non -metallic
The mineral test was used if a geologist refers to a mineral as metallic is luster because luster gives a way in which a metal reflects the light.
If a mineral is metallic then it will reflect light.
Hence, Luster was used if a geologist refers to a mineral as metallic.