Question

1. which is an example of a mineral whose streak cannot be determined with a porcelain streak plate? a. hematite b. gold c. feldspar d. magnetite

Explanation:

The hardness of a porcelain streak - plate is about 7 on the Mohs scale. Feldspar has a hardness of about 6 - 6.5 on the Mohs scale and will leave a streak on the porcelain plate. Hematite and magnetite are also softer than the porcelain plate and can leave streaks. Gold is a soft metal, but its streak can be determined. Minerals harder than the porcelain plate (hardness > 7) cannot have their streaks determined on it. Feldspar is the only option among the given ones that is too hard for the porcelain streak - plate to determine its streak.

Answer:

C. feldspar