Which mineral test was used if a geologist refers to a mineral as metallic?

Streak

Hardness

Luster

Magnetism

Answer: Luster

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.

Streak. It couldn't be hardness because some minerals are soft and metallic, and some are hard and metallic. Also, it can't be luster, because most gems are minerals, and most luster, but they're not metallic. And it can't be magnetism, because magnetite, the only magnetic mineral, is not really metallic.