Which is not a characteristic common to all minerals metallic luster orderly crystalline structure solid substance

Which medullary index indicates a human hair? a. 0.653 b. 0.733 c. 0.516 d. 0.256

Can someone i have no idea of how to do this.

Which of the following is the earliest era of earth's geologic time scale? cenozoic mesozoic precambrian paleozoic