For the majority of minerals,the streak color obtained when the mineral is scratched against a porcelain plate is ____________.

A)likely to be diagnostic only if the mineral is hard enough to scratch porcelain
B)more variable than the color in a hand sample among crystals
C)less variable than the color in a hand sample among crystals
D)always dark brown or black

Question

For the majority of minerals,the streak color obtained when the mineral is scratched against a porcelain plate is ____________.

A)likely to be diagnostic only if the mineral is hard enough to scratch porcelain 
B)more variable than the color in a hand sample among crystals 
C)less variable than the color in a hand sample among crystals 
D)always dark brown or black

Quizplus · Accepted Answer

The streak color obtained when a mineral is scratched against a porcelain plate is less variable than the color in a hand sample among crystals because it shows the true color of the mineral's powder. This is because the streak is produced by the finely powdered mineral rubbing off onto the plate. This color is not dependent on the surface features, impurities or weathering that can affect the color of a crystal.

For the Majority of Minerals,the Streak Color Obtained When the Mineral