Definitions

Mudstone is a fine grained clastic sedimentary rock and composed of silt-sized and clay-sized particles. Mudstones often are mistaken for siltstone or claystone, but the difference lies in the grainsize. The grainsize of mudstone lies exactly between that of silt and clay. To distinguish them the following definitions can be used:

• Siltstone – more than half of the composition is silt-sized particles.
• Claystone – more than half of the composition is clay-sized particles.
• Mudstone – hardened mud; a mix of silt and clay sized particles.

Characteristics

Mudstone has a variable color scheme the reason for this are the minerals that can be present, which are: clay minerals, quartz, feldspar, mica, iron oxides and carbonaceous content. Mudstone is very smooth to touch and has a hardness of 2.5 on the Mohr scale.

References

• https://geologyscience.com/