Dyke rock is igneous rock that forms when magma solidifies in a narrow fissure or dyke in the Earth’s crust, partway between the depths and the surface. Because of this it occupies an intermediate position between plutonic and volcanic rock.
Application
Magma can cool in three ways, and the way it cools determines the structure of the resulting rock:
- Plutonic (intrusive) rock solidifies slowly deep within the Earth’s crust. The slow cooling allows large crystals to grow; granite is the best-known example.
- Volcanic (extrusive) rock solidifies quickly at or near the surface, so the crystals stay small and fine-grained; basalt is typical of this group.
- Dyke rock solidifies in a dyke or fissure at an intermediate depth. Cooling proceeds faster than for plutonic rock but slower than for volcanic rock, so the grain size falls neatly in between.
A well-known example of dyke rock is porphyry, recognisable by larger crystals set within a finer groundmass. This so-called porphyritic texture arises because some crystals had already grown before the magma finally solidified.
Thanks to its high hardness and wear resistance, dyke rock is widely used as natural stone:
- As paving material: setts, cobbles and slabs for roads and squares
- As crushed stone and aggregate in road construction and the concrete industry
- As facade and decorative cladding for its attractive crystal structure
Its durability and weather resistance make dyke rock especially suitable for heavily loaded outdoor applications.
Related terms
- Natural stone
- Concrete
- Bricklaying
- Foundation
Learn more about construction terms in our knowledge base on fredsdiyplans.com.