What are the viscosity values of different rocks and minerals? Please provide references.?

Answer 1

Rocks and minerals, despite being solid, certainly can exhibit viscous behavior. Some researchers, such as David Yuen at the University of Minnesota, use constraints such as post-glacial rebound to determine the effective viscosity of the mantle, which is predominantly solid. Other researchers, such as Shun Karato at Yale and David Kohlstedt at the University of Minnesota, deform minerals and rocks under high-pressure, high temperature conditions in order to measure their strength at different strain rates. I had the pleasure of working in the research labs of Karato and Kohlstedt while working on my PhD and postdoctoral research.

It is easy for most people to understand that materials are more ductile at higher temperatures. Butter, when frozen, breaks apart in brittle chunks when it is stressed. The same stick of butter will flow quite easily at 80 ºF, even though this temperature is 10º below the melting temperature. Rock or mineral samples usually need to be deformed at temperatures over 1000 ºC to achieve ductile behavior. A cylindrical-shaped sample will exhibit a barrel shape after deformation.

Getting back to your original question, you can't specify the viscosity of a rock or mineral unless you give the temperature, pressure, water fugacity, grain size and strain rate (or stress) of the rock/mineral. Even at a fixed temperature, the viscosity can vary by orders of magnitude if it is in the power-law creep domain.

To give you an order of magnitude for viscosity, the mantle, which is composed primarily of olivine and pyroxene, is estimated to have a viscosity between 10^19 and 10^21 Pa⋅s. The viscosity for refractory materials like spinel tend to be very high right up to the melting point. Other materials such as salt have a relatively low viscosity. To compare the viscosity of different minerals and rocks, however, you need to specify the conditions of deformation.

The link to the website below should give you some idea about the different deformation regimes and the viscosity for a couple of minerals.

Answer 2

Rocks and minerals are generally solids and do not exhibit viscosity.
Magma is molten rock and the viscosity will be determined by temperature and mineralogy