Siltstone

About it

Fine sedimentary rock of silt grains: smoother than sandstone but faintly gritty against a fingernail or tooth, unlike shale and mudstone. Often thin-bedded with ripple marks or trace fossils.

Type

Rock (sedimentary)

Group

Sedimentary (clastic)

Lustre

dull

Colours

grey, brown, green, red, tan

Transparency

opaque

Typical values: real specimens vary. For more, see mindat.org.