John investigated the properties of two minerals and recorded his observations: Feldspar is gray, dull, and breaks apart when it is rubbed.
Quartz is purple, glassy, and leaves a white streak when rubbed against a streak plate.

What observations show evidence about the luster of the two minerals? (2 points)
a
Feldspar is dull, while quartz is glassy.

b
Feldspar is gray, while quartz is purple.

c
Feldspar breaks apart when it is rubbed, while quartz does not.

d
Quartz leaves a white streak when rubbed, while feldspar does not.

Please use an answer like A B C or D

DO NOT USE THIS ANSWER!!
The solid earth is made of rocks, which are made of minerals. To understand rocks you need to become familiar with minerals and how they are identified. This outcome gives you the background needed to understand the terms used in identifying minerals.