Dyke-rock

Appears to be a fine-grained dioritic dyke rock, but is too dirty and stained to be satisfactorily examined.

If the dyke is of great thickness the centre may be coarsely crystalline as a deep-seated plutonic rock and this makes it difficult to distinguish a dyke rock in hand specimen.

As a dyke is made of igneous rock, it is usually possible to date it by radiometric dating methods, which give an absolute age for the dyke rock.