Rock Topics

Common Sedimentary Rocks (Part 2)


Limestone is a very common sedimentary rock.  It is often made up of various sizes of animal shells.  Limestone fizzes with the application of dilute hydrochloric acid because it contains calcite.

Fossiliferous Limestone
Limestone (Photograph by Parvinder Sethi)


Dolostone is a common sedimentary rock similar to limestone.  It is typically a dull gray.  It can be identified by scratching the surface and exposing the scratches to dilute hydrochloric acid.  Only the scratches on dolostone will fizz.

Dolostone (Photograph by Parvinder Sethi)


Chert is a chemical sedimentary rock composed of microcrystalline quartz.  In its gray form, it is called flint.  It makes sparks when struck against steel.

ChertChert (Photograph by Parvinder Sethi)