Question

luster is the way light is reflected by a minerals surface and how brilliant or dull it is. a minerals luster can be metallic or nonmetallic. metallic means that a mineral is shiny and looks like metal. galena and gold have metallic luster. there are different types of nonmetallic luster. some nonmetallic minerals have a vitreous, or glassy, luster. others have a pearly luster. still others have a greasy luster that looks oily. diamonds have what is called an adamantine luster. thats a rare luster that makes diamonds sparkle. minerals that are oily - looking have a(n) choose one option a vitreous luster. b metallic luster. c greasy luster. d adamantine luster.

Explanation:

The text clearly states that "Still others have a greasy luster that looks oily." So, when a mineral is oily - looking, it has a greasy luster.

Answer:

C. greasy luster.