How hard is gneiss on the mohs scale?

Answer 1

== == The Mohs Scale is used to determine the relative hardness of a mineral as a comparison to another mineral. Because granite is a rock composed of multiple minerals, only crystals of specific minerals within the granite would be tested for hardness. Granite is typically composed of quartz (Mohs-7), potassium feldspar (Mohs-6), and biotite and muscovite micas (Mohs-2.0-2.5). The varying amounts of these minerals would made it difficult to assign a specific Mohs hardness to granite generally. Besides the Mohs scale, which only measures the hardness of minerals by their ability to scratch or be scratched by another mineral, the hardness of granite is greater than many other rock types because of its interlocking mineral structure which is a result of the growth of mineral crystals out of a molten state. As different minerals reach their point of crystallization in the Bowen's reaction series, they form in the space that remains in which to form, resulting in crystals which are tightly interlocked with each other.

Answer 2

Rocks will have variable hardness readings, but gneiss is considered to have a hardness of roughly 7, the same as quartz.

Answer 3

Gneiss is a rock composed of minerals of varying Mohs hardness and therefore would not have a specific Mohs hardness.

Answer 4

3