There are about 2000 types of minerals found on Earth, but only some of these minerals form rocks. What is the number of these minerals?

There are about 2000 types of minerals found on Earth, but only some o

1.	There are about 2000 types of minerals found on Earth, but only some of these minerals form rocks. What is the number of these minerals?
A.	10 ,
B.	20 ,
C.	150 ,
D.	500 ,
Answer» C. 150 ,