Can we know the uniaxial compressive strength of minerals, say quartz or calcite? Are there any standardized values or can we use indirect approaches to estimate, like hardness tests?
Soft rock is a term that usually refers to a rock material with a uniaxial compressive strength (UCS) less than 20 MPa. This low strength range might be influenced by physical characteristics, such as size, saturation, weathering and mineral content. strength reduced significantly in saturation. The reduction also affects by weathering, the strength of distinctly weathered rocks were lower than that of partially weathered rocks. The influence of water on rock strength has been known for years, it is also known that strength reduction due to saturation varies from one rock to another.
International Society for Rock Mechanics (ISRM), Rock Characterization, Testing and Monitoring, ISRM Suggested Methods and you can make correlations according to after you work according to classification of rocks. you can choose your mineral and study all cases in if this there is change in environments
Yes, indirect method is possible. The compressive strength of different minerals including quartz can be deduced from the hardness indices (e.g. quartz, feldspar and mica are 200, 180, and 120 MPa respectively). You can find more details about mineral properties in the following literature [ 1. Wang F, Konietzky H, Herbst M. Influence of heterogeneity on thermo-mechanical behaviour of rocks. Comput Geotech. 2019;116(May):103184. doi:10.1016/j.compgeo.2019.103184 (2) Tham LG, Cheung YK, Tang CA. Numerical simulation of the failure process of rocks. Tamkang J Sci Eng. 2001;4(4):239-252. ],
Maybe you can find the elastic properties of minerals in the paper given below:
"THE ELASTIC PROPERTIES OF CERTAIN BASIC ROCKS AND
OF THEIR CONSTITUENT MINERALS" Adams and Gibson, 1929. Geophysics.
regards,
serdar
In my view, the UCS of rock-forming minerals probably can be deduced from their hardness values which are often reported in the literature; see more information in a recent publication: Shang (2020) Rupture of veined granite in polyaxial compression: Insights from three-dimensional Discrete Element Method modelling. JGR Solid Earth. DOI: 10.1029/2019JB019052
Dear Dr. Shang
You can use the nanoindentation methods to obtain the UCS of particular minerals in rocks through using the reverse analysis method.
Cheers
Zhaoyang
In my opinion, since rocks are combinations of rock-forming minerals, it is not possible in nature to find a rock composed completely from a single rock-forming mineral crystal. Even a rock formed from a single mineral constitute, say quartzite or calcite, the size of the crystal forming the rock will not be enough to measure experimentally in standard laboratory tests. If you can find a mineral crystal in nature comporable to specimen size used in standard rock mechanics tests , you can determine its mechnical properties.
Hi Shang,
In my opinion, it is possible. U can use "Mohs Hardness Scale" for prediction of UCS.
With Best regards
Ch.Vijayakumar