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, as it is not influenced by impurities or surface weathering. It can therefore be a more reliable diagnostic characteristic to help identify a mineral. However, it is important to note that this diagnostic property is only applicable for minerals that are harder than the porcelain plate, as otherwise the streak will be produced by the plate instead of the mineral.

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