Author Question: Students new to mineral identification often confuse shiny, dark-colored nonmetallic minerals for ... (Read 60 times)

jazziefee · **on:** Jul 16, 2018

Students new to mineral identification often confuse shiny, dark-colored nonmetallic minerals for those minerals with a metallic luster. Explain how streak can be useful for telling these minerals apart.

What will be an ideal response?

Question 2

Two unknown minerals are placed before you for identification. You decide to test each mineral's hardness. Mineral A will scratch a piece of glass. Mineral B will not. Which mineral is harder? How do they compare to the specific hardness of the glass?

What will be an ideal response?

dlook33 · **Reply #1 on:** Jul 16, 2018

Answer to Question 1

Answer: Metallic minerals generally have a dark-colored streak, whereas nonmetallic minerals generally have a light-colored streak.

Answer to Question 2

Answer: Mineral A is harder. Specifically, it is harder than glass (5.5) because it made a scratch. Mineral B is softer than 5.5 because it did not scratch the glass.