Igneous Rock - Microtonalite

This rock sample was cored from about 25m below ground level in Kuching. 

Imagine a few hundred millions years ago, the magma punched through the earth crust, wanted to get out to the surface. But it lost its steam and stopped 25m below the ground. There it cooled and formed this fine grained rock.

It it had managed to come out of the earth surface, it would cool faster and formed coarse grained Granite.

It it had come out of the ocean floor, it would had formed Basalt.

This wonderful work of Nature played around temperature and pressure to form different kinds of rock structures !

Igneous rocks are quite durable,hard and are often used for civil engineering materials. 

Granite is especially excellent for making road bases and concrete.